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“ Abstracts from the Meteorological Observations taken on the assumption that a fly with five legs is as good as at the Stations of the Royal Engineers (including 15 one with six, and if one snipped off a piece of a known lig Colonial Stations) in the Year 1853-4, with Notes on that fly could be identified when caught again. Six serie Meteorological Subjects.'

of experiments could be made. It worked admirably. The “ Abstracts from the Meteorological Observations taken experiments want repeating on a larger scale (I hop 10 at the Stations of the Royal Engineers (comprising 13 do it on the Semliki), but I have shown clearly that the British and 18 Colonial Stations) in the Years 1853-4, range is at least a mile. This is the reason why the 1854-5, 1855-6, 1856–7, 1857-8, and 1858--9."

breeding places have eluded search so long. Abstracts from the Meteorological Observations taken

(Signed) ARTHUR G. BAGSHAW! in the Years 1860-61, at the Royal Engineer Office, New “ Albert Edward Lake, September 1, 1900." Westminster, British Columbia."

These volumes will be issued without payment.
I may also mention at the same time that the Meteor-

Suspended Germination of Seeds. ological Committee, acting in accordance with the recom- IN Mr. Claridge Druce's letter in NATURE of Octobre 11 mendation of the fourth International Conference he rightly remarks that in order to prove the suspended Scientific Aëronautics, has undertaken to subscribe for germination of seeds over long periods, instances are rea number of copies of the international publication of the quired in which the factors of wind-carried seeds, &c., can observations of the upper air on the “ international days," be with some certainty eliminated. The following case, which will be issued by Prof. Hergesell, the president of though not absolutely conclusive, may still be of interest the commission. I shall be glad to know whether any Personally I am of opinion that the seed of Digitalis scientific institution or library wishes to subscribe for a docs preserve its germinating power for a considerable time. copy of this publication. The amount of the subscription A few years ago I cleared a space, speaking from memory. is il. per annum.

W. N. Suaw. of say forty yards by thirty yards, occupied by old Portugal

laurels 25 feet to 30 feet high, planted fully sixty year The Breeding Habits of the Tsetse-fly.

ago, with Rhod. ponticum lining the path in front; the

space, except on the path side, is surrounded by thick I SHOULD be greatly obliged if you could find space in coverts. The nearest growing foxgloves were to the west your columns for the following extracts from a letter which along a 6-feet path running parallel with the long side of I have received from my friend Dr. A. G. Bagshawe the cleared area, and distant, say, ten yards; both sides announcing the discovery, I believe for the first time, of of this intervening space are lined by old rhododendrons. the pupæ of the tsetse-fly (Glossina palpalis) in nature. seed blown along would fall on the path or the edge of this species of fly is now known to be the agent which the clearing. The laurels were removed in January and disseminates the infection of sleeping sickness, any dis- February, when all, or nearly all, the seed would have coveries relating to its breeding habits are of the utmost been shed. Notwithstanding this, the next spring the whole importance from the point of view of devising measures of the cleared ground was covered with a uniform carpet for extirpating the fly or checking its increase. Together of seedlings, practically hiding the bare ground. It sem with my colleagues Lieuts. Gray and Tulloch, I spent a to me that, even if some wind-blown seed penetrated the great deal of time, when I was in Entebbe, in searching evergreen barrier, the seedlings would have appeared in for the pupæ of the fly, and we offered the native boys a patches. rupee each for them, but all our efforts to find them in I have known many other somewhat similar instances, nature were unsuccessful, although captive fies deposited but none quite so specialised as the above. I may add this great numbers of pupæ in our cages. I ought, perhaps, to the spot is exceptionally protected from wind, having tali explain at this point that the tsetse-fly is viviparous, and forest trees on all sides. produces a full-grown larva, one at a time; the larva is

ARCHIBALD BUCHAN-HEPERY. of a light yellowish tint when born, and wriggles about Smeaton-Hepburn, Prestonkirk. actively for an hour or so, and then turns in a short time to a dark brown pupa, about the size of a grain of wheat. Dr. Bagshawe, who is already well known for the

Biometry and Biology. botanical collections he has sent home, has succeeded where

Owing to the proof of my letter in last week's PATUTE we failed, and as I do not know what steps he has taken reaching me too late for careful revision, one or two clip to secure the priority for this most important discovery, I escaped notice. Of these, I would wish to direct attration hasten to make it public on his behalf. It will be seen to the interchange of the words intra-racial and inter-ra 18 that the pupäe have been found in the banana plantations. in the second paragraph on p. 609 (column 1, line 141. Since bananas are the staple food of the Baganda, it would

KARL PEARSOX. be impossible to destroy the plantations without creating Biometric Laboratory, University College, London, a famine. I may mention, however, that we found the October 19. tsetse-fly swarming on the deserted island of Kimmi, on the Victoria Nyanza, where there were no plantations, so that this is perhaps not its only breeding place.


TRAVELLING. Lister Institute of Preventive Medicine, October 17.

THE Salisbury railway accident, being followed (Extract from Dr. Bagshawe's Letter.)

after no very long period by the somewhat On August 29 I got them (the pupa] at last. I had

similar disaster at Grantham, undoubtedly raid marked down a particular spot as likely, and had pitched feeling of considerable uneasiness in the public mind. my camp near by to search. Along the lake shore for The recent publication by the Board of Trade about 100 yards was a belt of bananas 10-20 (40?) yards Major Pringle's report on the former calamity shuul in width, and behind that undergrowth, going back 100 do something to allay this apprehension, is only for vards or more. Fly were thick and bothered one up to cause it shows that the cause of the derailment a sunset.

the train was not “ mysterious," but is fully to lo On the second day one of the porters I had coached

explained. That the evil we know is less alarmin: brought me a pupa while I was searching a hole in a tree.

than one which vaguely threatens is a fact for whina He had found it among the banana rootlets. I searched there at once, and soon found some empty pupa cases.

we have classic authority. The next day I had a lot of my people at work and 53

The accident occurred on July 1 at the Salitse pupą were found, all in the loose crumbling soil round

Station of the London and South-Western Ruila the bananas. In the scrub behind there are none to be

the train being the special boat express from Plyora got.

to London, carrying passengers who had arriind to “I made a series of experiments lately to find out how the American liner New York. The train consiste long a stretch of river the individual Av haunts. I started of four eight-wheeled vehicles hauled by a favor coupled engine with a leading bogie, having an eight-curve is 3; inches. It was on this part of the line wheeled bogie tender. The coaches were not of that the accident occurred, the overturned engine excessive length, the longest being 48 feet, and all being found at the termination of the curve, and just were on bogies; the engine was one of the company's in front of facing points with reverse

curves of usual modern express type, and although the boiler 7 chains radius; naturally there could be no superis mounted higher than was formerly the practice, elevation at the points. The report states that the the train was well calculated to run safely round three leading vehicles of the express were overturned curves under usual conditions : yet it was a curve that in various directions, the frames stripped of woodwork caused the accident. In saying this we are not and completely destroyed. The fourth vehicle fared verbally in agreement with Major Pringle's report or little better. Comparatively little damage was done with the verdict of the coroner's jury at the inquest to the last vehicle, which came to rest in an upright on the unfortunate victims, both of which attribute position, with the last pair of wheels on the proper the accident to excessive speed. No doubt the speed rails. The engine and tender were both overturned at which the curve was taken was too high, but if on their right sides, but less damage was done than the curve had not been so sharp the speed would might have been expected, and the engine was shortly have been perfecuy safe; in fact, it was the curve afterwards hauled to Nine Elms on its own wheels. which was the abnormal feature, the speed being Five vans of the milk train were completely deordinary for ordinary conditions. It may seem like stroyed, and five were damaged. This destruction of

plitting hairs to cavil over terms in this manner, rolling-stock was accompanied by remarkably little but the matter has greater significance than may danage to permanent way on the up line over which appear. If we allow the accident to have been due the express was running, but a length of about forty simply to speed, then the railway authorities have yards of the down line was torn out and destroyed. done all that they can do when they order drivers- The weight of the engine was nearly 54 tons as they always have done—to reduce speed to within safe limits; but if it is stated that the accident was

(53 tons 19 cwt.), 16 tons 17 cut. being on the leaddue to excessive curvature of track, then the company and 18 tons on the trailing axle. The tender weighed

ing bogie, 19 tons 2 cwt, on the leading driving axle, will appear not to have done all that is possible until they flatten the curve. Whether the danger warrants

44 tons 17 cwt., 23 tons 2 cwt. being on the leading the expenditure is another matter, but we may re

bogie, and 21 tons 15 cwt. on the trailing bogie.

The centre of gravity of the engine was calculated at member that so long as drivers are human and liable about 5 feet above the rail-level, and that of the tender to err, the chance of disaster is always present whilst such an abnormal curve exists on a main line over

at about 4i feet. which, express trains run; in other words, if the

So far we have most of the chief data generally Salisbury curve did not exist accident from the same

at command for calculating what would be the limit cause would be impossible.

of safe speed for travelling over the part of the

line where the accident occurred. Calculations for Speed is always a doubtful point in the elucidation of the cause of accident, but there is no doubt, from

the centre of gravity of an engine are somewhat the evidence at the inquest and the Board of Trade

tedious, even when all data are at command, and the inquiry, that the train was travelling very greatly in

figures given appear somewhat low for an engine of excess of the thirty miles an hour laid down by the

the type. In former days this would have been of regulations as safe for the curve immediately to the

less consequence, but the tendency to raise the boiler, east of Salisbury station. One witness estimated the

so that the chimney becomes nothing more than a

• frill round a hole speed to have been as high as seventy miles an hour,

as a railway engineer recently and Major Pringle considers that possibly this may not

said-makes the centre of gravity a factor that needs have been an extravagant estimate. When the engine

more attention, although the effect in this respect of and tender left the line it came into violent contact

the modern high boiler is far more apparent than

real. with a milk train moving on the down line, and the wreckage also struck a light engine standing in a

It is unfortunate that our chief railways were debay close by. Particulars of the loss of life have been signed for lower speeds than are now required, and fully published, and will be sufficient to say that altogether for more primitive conditions; thus it is on the express twenty-four passengers were killed, possible that when Salisbury Station was built it was seven were seriously injured, the engine-driver and

not anticipated that a train would ever run through, fireman were killed, and a ticket collector and two

and the curve of 8 chains would be without danger waiters on the dining car of the milk train and the fireman of the light engine with a centre of gravity 5 feet above the rails, when were injured. The guard for a stopping train.

Major Pringle says that the engine in question, were also killed, and the driver was badly scalded. The chief interest of Major Pringle's report, as in

traversing a curve of 8 chains, would be in unstable all reports of this nature, centres in his conclusion equilibrium at a speed of about sixty-seven to sixtyas to the probable cause of the accident. Speaking eight miles per hour, even if full allowance were made at large, there is no doubt, as we have stated, but

for the beneficial effect of 33 inches superelevation. that the disaster was due to high speed on an 'awkMajor Pringle does not give his calculations, but, ward curve, and the evidence all points to the fact

as he says, the result may be taken as agreeing that the engine and tender turned over bodily; how with modern formulæ. The rule

where the forces set up acted so as to bring about the result is the problem that remains to be solved.

\=width of gauge in feet, V=velocity in miles per According to the plan of this part of the line, given hour, R=radius of curve in feet, and É relevation of in the report, the up line is straight through the outer rail in inches; or if the speed V were expressed station, but at the eastern end of the platform a in feet per second the formula would become curve to the left of ten chains radius (compound) ex- W V2!gR, where g is 32.2.

If the formula were tenris for a distance of about ninety-two yards. In the used to calculate the superelevation for a speed of body of the report is a statement attributing a radius sixty miles per hour, it would give superelevation of of eight chains to the curve, this representing the 25.6 inches; on the other hand, at the speed of thirty sharpest part of it. There is a rising gradient of miles an hour—that laid down as a maximum by the i in 158, and the maximum superelevation on the railway company's engineers—the rule would give

WV2 1'25 R



54 x 882


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Therefore CH=CM < (68–8)="(-á).



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superelevation of 6.4 inches. The maximum super- Working backwards with the same data, and elevation on the South-Western Railway is 6 inches, assuming the resultant to pass through A, it will be and it is, of course, altogether impossible to work with found that the critical speed would be practically any such superelevation as more than 2 feet. It will sixty-six miles per hour. be understood that the whole of the constraining force In order to calculate CH quickly and with an required to keep the engine moving in the curve is approximation sufficient for practical purposes, the supplied by the resolved component of the weight of above working may be very much simplified by the the engine acting parallel to the plane of the radius following formula, which has been suggested by Prof. towards the centre of curvature.

Dalby :It will be evident, therefore, that superelevation is a remedy of limited efficacy for a serious defect. The

= R-6), where e= superelevation in inches,


3R G centrifugal force at sixty miles per hour (a speed | G--the gauge in inches, V=the velocity in feet per second, that the evidence of figures shows to have been ex- g=32'2, R=radius of curve in feet, h= height of cedire of ceeded, but which we adopt as a convenient standard) gravity of engine above the rail level in feet. would be or, approximately, 24 tons (24 597).

The way in which the formula is obtained from 32'2 x 528

Fig. 1 is as follows: The accompanying diagram (Fig. 1) illustrates the

AE resultant of the two opposing forces acting on the



AB-G engine.

QR WV? V? M=centre of gravity of the engine 5 feet above rail


very approximately. level. The line MQ=the weight of the engine, and

V2 MF=the centrifugal force at sixty miles an hour to

Therelore (=-B= approximately. the

scale. Completing the parallelogram MFRQ, then MR=the resultant of the two forces.

V2 Producing MR, it cuts the rail-level at the point H,

SR which is 5.29 inches inside the outer rail; AE is the The above gives a very nearly correct result when superelevation. There would only be, therefore, the point H is in the neighbourhood of C, as it should

be. The error increases as H approaches A.

We may compare the value of CH obtained by the two methods; we have already shown by the exact method that CH=23 inches. Applying the approximate formula CH=23.6 inches.

From the foregoing calculations it would appear that if the train were travelling at a speed of more than sixty-six miles an hour the engine would turn over sideways, but it will be understood that deductions drawn in this way are not proof, though they may be evidence, of what has occurred. The speed of the train is, of course, a very indeterminais quantity; the maximum superelevation was, as stated. 3) inches, but, to judge by the plan, this did not extend on the curve for a greater distance than about 50 feet, and it would appear that at the spot where the trouble commenced (to judge by the damage to the line) the superelevation was somewhat less. Again, in placing the position of the centre of gravity of the engine, there are various unknown factors which it would be necessary to take into (orisideration to enable a true result to be reached; ica instance, there is the unequal compression of th springs causing lateral displacement of the centre of gravity, rush of water in the boiler, and the extent of wear of wheels and rails.

G. R. DUXELL about 5 inches between the points A and H. The narrowness of the margin of safety with the data assumed. is indicated very clearly in the diagram by ESTIMATION OF BLOOD-PRESSI'RE. the nearness of H to A; should H coincide with A, the engine is just on the point of turning over.


HE subject of blood-pressure is one of grin! The working out of the problem is as follows :-

interest both to the physiologist and the cliare

physician. By blood-pressure is meant the pressure MQ = 54 tons.

which the blood exerts on the interior of the h-aoi MF = 24.596 tons.

and blood vessels, but it is chiefly with the vasculo MC = 60 inches. AE=3.5 inches.

blood-pressure--arterial, capillary, and venous-to" AB= 56.5 inches.

the physician deals. Our conception of intravascui.. MF 24.596

pressure is facilitated by considering what happenin MQ 54 =0:45548

when an aperture is made in an artery, capillars in Q = 24° 29'

vein of a living animal. In the case of the arir** AE

3.5 sine B=sine n=

the blood squirts out with considerable force, to

height of the jet measuring the pressure exerted. B=3° 33'

the interior of the vessel. Experiment shows that the 0=° - B = 24° 29' - 3° 33'= 20° 56'

pressure falls slowly from the heart to the region CH= MC tan ¢ = 60 x 0383= 23(app.)

the smallest arteries, or arterioles, where there is AH = 28 25 – 23=5] inches.

considerable fall, the pressure in the capillaries







tan =

AB - 56.5 = 0·0619



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veins being comparatively low; in the large veins methods is available for clinical purposes. Recently, opening into the right heart it may, indeed, be however, a method has been devised in which the minus, owing to the suction action of the thorax, and employment of the knife can be dispensed with, and hence when these veins are cut air may actually be one, moreover, yielding results quite as accurate as sucked into the blood-stream.

those just referred to. It consists in enveloping some The vascular blood-pressure is subject to consider- part of the upper extremity-arm, forearm, or fingerable variation both in health and disease, and it will in a gutta-percha bag, and connecting the latter, by readily be seen that its accurate estimation is of great i means of a tubing, with a manometer. The bag is clinical value. To take an illustrative case. In / blown up until the pulse on the distal side of it is certain poisoned states of the blood the small arteries obliterated, the pressure then registered by the manoundergo considerable contraction; in consequence of meter representing the “ systolic,” or “obliterative"


The diastolic" pressure,

that obtaining between

the heart beats, Amster, LONDON

is measured by noting the excursions of the manometric index produced by the pul

sations of the F16. 1.-Dr. George Oliver's Hæmomanometer (reduced to half size). A is the graduated glass tube along which moves the

coloured spirit-index, represented by the dark curved line at the right-hand bend; B is the open end on to which fits artery; it is held the rubber tube communicating with the enveloping bag, or armlet; c is kept closed by means of an air-block, while that the maximum the blood-pressure is being taken.


when the pressure this the blood cannot pass into the capillaries and on the artery is just sufficient to balance the diastolic veins with its wonted facility, and tends to be dammed pressure. back upon the large arteries and heart; in other Hitherto the manometer most frequently used in words, the blood-pressure rises in the left ventricle these observations has been the ordinary mercurial and in the whole arterial tree proximal to the con- one; but Dr. George Oliver, of Harrogate, has tracted area, and this heightened pressure is further recently devised an instrument which is not only more augmented by an increase in the force of the heart- handy, but would appear to give more accurate readbeat, called forth by the necessity to overcome the ings than the mercurial manometer. It consists of increased resistance. An increased strain is thus put a fine bored glass tube (Figs. I and 2) which during upon the heart and arteries, and this, if long con- use is kept closed at one end, and connected at the tinued, may lead to disease in them; and in this way such serious affections as aneurism, heart-disease, and apoplexy may be brought about. The importance of early detecting such cases of augmented pressure is apparent, in that it enables steps to be taken to correct the underlying faulty condition of blood, and thus to ward off grave consequences.

Until recently the physician had to be content to rely upon his sense of touch in estimating blood-pressure, and thus it was that the older physicians spoke of a “hard” and “soft” pulse, the former indicating a high and the latter a low bloodpressure. More modern physicians describe the pulse as “compressible" or “incompressible,” or

' the vessel being in a state of high or low tension,” according to the readiness with which it yields to the pressure of the finger. This tactile method is, however, far from trustworthy. Not only is long experience needed to acquire Fig. 2.- Method of employing Dr. Oliver's hæmomanometer. even moderate efficiency in it, but from

D is the armlet; c is the rubber tubing connecting the armlet with the glass tube ; a variety of causes the most skilful are B is the rubber ball for inflating the armlet; this is provided with a screw (covered by the liable to make false estimates by its

thumb), by means of which the armlet and tubing may be gradually deflated. means; nor do the findings admit of accurate record. In short, though useful as a rough- other with the enveloping bag by means of elastic and-ready method, it lacks the precision needful for tubing. A minute drop of coloured spirit introduced scientific observation.

into the glass tube serves as the index. At the comThe earliest method of estimating the arterial mencement of an observation the index is at zero, blood-pressure consisted in cutting the artery of an which is situated at the open end of the tube. As the animal and observing the height to which the blood bag is blown up the index is driven onwards, comwas forced out. Later the more delicate plan was pressing the air in front of it, and advancing with adopted of connecting the interior of the vessel with every increment of pressure. The instrument is a mercurial manometer, by means of an elastic tubing readily graduated by means of a mercurial manofilled with saline solution. Clearly neither of these meter. It will be seen from this description that the

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A is the bæmomanometer ;

pressure on either side of the index is equal, a circum- We have, it is true, neat and compendious biographies stance which tends to reduce to a minimum the errors of Mendel, but they reveal to us little of the man due to inertia of the index, and this is of great advant- himself, and it is still a distant and mysterious monk age in estimating the diastolic blood-pressure.

that appears to us, with his classical peas in his In a valuable booklet recently issued by Dr. Oliver I cloister garden. The value of these letters is that on blood-pressure gauging, he sets forth some of the they lift the veil for us here and there, and extend more important results he has arrived at by means to us an invitation to a “private view" of his work, of this ingenious instrument. This physician attaches and offer us an opportunity of a nearer acquaintance considerable importance to the study of the pressure with its author. in the smallest arteries and capillaries by means of The correspondence was begun by Mendel, who a digital bag. He finds that while arteriolar dilata- wrote to Nägeli on New Year's Eve, 1866. In this tion lowers the pressure in the larger arteries by letter he referred to Nägeli's great services to the lessening peripheral resistance, it tends to augment study of hybrids occurring in nature, mentioned his that in the capillaries and pre-capillary vessels by own results with peas, gave an account of some new increasing their supply of blood. During muscular experiments he was starting with the hawkweed, exercise, on the other hand, the pressure throughout and ended with what was probably the reason for his the entire length of the systemic arteries is increased, writing, an appeal for help and advice with these owing to the fact that the dilatation of the arterioles experiments. is accompanied by a considerable augmentation of Nägeli answered on February 24, 1867, addressing cardiac action. The essential circulatory change Mendel as Verehrtester Herr College. He recomie attending upon digestion, so far as the systemic mended some hawksweed species for the proposed essystem is concerned, is, according to Dr. Oliver, an periments, but the chief interest the letter has for us increment in the capillary and pre-capillary pressure, lies in the criticism which it contains of Mendel's wellwhereby an increase of lymph-exudation is effected, known formulæ. Nägeli said : “ Die Formeln dürften and the products of recently digested food thus Sie wohl ebenfalls für empirische halten, da dieselben speedily conveyed to the tissues. Such an augment- als rationellen nicht zu erweisen wären." Mendel's ation in the exudation of lymph he claims to have reply to this criticism is a little difficult to underdemonstrated.

stand, and Prof. Correns remarks in a footnote, “ Ich Of special interest are Dr. Oliver's observations on weiss nicht, ob Mendel hier das, was Nägeli unter emthe blood-pressure of the aged and elderly. With pirischer und rationeller Formel meinte, ganz veradvancing years the smaller vessels tend to become standen hat. But I suggest Mendel's reply becomes rigid and impervious, and thus to lose their power of intelligible if we divide it into two sections (the first dilating in response to physiological requirements, of which ends with the sentence to which Correns's such as digestion and muscular exercise. When this note is appended), and regard each section as an happens the blood-pressure in them is found to be answer to one of two interpretations, of the criticism. habitually low, and to fail to rise readily during by Mendel, who I imagine was not quite sure what digestion, or as the result of administering such a Nägeli meant. In the first part of his answer Mende! drug as nitroglycerine, which normally dilates the interprets the criticism as meaning that the simple smaller arteries. In this way the physician is able formulæ, in which only one pair of characters is to gauge the condition of the blood-vessels with a concerned, are “empirical,” and that the complex precision which was quite impossible with the older ones, in which many are concerned, are “ rational." methods. In cases of premature degeneration of the I think we may be pretty sure that Nägeli did not blood-vessels, Dr. Oliver believes that much may be mean this; however, I am not here concerned with done to check the degenerative process. Among the what he did mean. methods he employs to this end is the administration Nor do I stop to discuss what Nägeli may have of certain substances the deficiency of which in blood meant when I come to consider the second section is thought by some to be largely responsible for the of Mendel's reply. The point is that it begins with phenomena of senility.

the words “Was schliesslich die Angaben uber die These brief references suffice to show the practical Verschiedenheit der von den Hybriden gebildeten value attaching to the clinical study of blood-pressure. Keimbläschen und Pollenzellen betrifft. ..." Mendel The student in this important branch of investigation is discussing an entirely different subject now, and he will find great help from Dr. Oliver's book, the more shows unconsciously by this fact that it never occurred so that only salient and practical points are dealt to him that Vägeli might mean by his criticism that with, and these in clear and simple language.

while of course it was impossible to deny the numerical proportion of the different categories

(1D:2DR: 1R), that was a very different thing frur MENDEL'S CORRESPONDENCE WITH

stating one's belief that the suggested interpretation VAGELI.

of that proportion (the random union of THESE letters constitute a valuable addition to the

50 D + 50 R with 50 D + 30 R name of one of the most remarkable figures in the

was true, and that it was very desirable that they history of biology-Gregor Mendel; for we doubt if

two entirely different things should not be confused. ever has so great a fame been built on the contents

Nägeli may or may not have meant this, but the of a single short paper. The fact that this paper

point of interest is that it did not occur to Mendel remained unknown from 1863, when it was published,

that he might have done, which shows that so far until 1900, when it was rediscovered, is both the

was he from confusing these two things that the pose measure of how much Mendel was before his time

sibility that he might have done never occurred to and the reason for the uniqueness of the picture of

him as an interpretation of Nägeli's criticism, him which presents itself to the eyes of most of us. I have discussed this at some length because such

1 “Studies in Blood-pressure : Physiological and Clinical." By Dr. confusion is not rare among modern students of George Oliver. (London: H. K. Lewis, 1906.) Price 25. 61. net. 9 “Gregor Mendel's Briefe an Carl Nageli, 1866-73. Ein Nachtrag zu

heredity. Bastardierungsversuchen

Edited by This second letter of Mendel's was accompanied by Abhandl. d. K. S. Gesellsch. d. Wissensch., math.-phys Kl. xxix. iii. Pp. 189-264. (Leipzig: B. G. Teubner, 1905.)

several packets of peas, which were sent to tt 3 marks.

Nägeli's doubts at rest.


den veröffentlichten C. Correns.


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