set before you on Polystomella were obtained by both of us independently of one another, though I had not obtained evidence of more than one division of the spore-nuclei or of the number of the flagella of the zoospores.

The evidence pointed strongly in the direction of the view that the foraminiferal life-history consists of an alternation of generations. While the megalospheric form would, on this hypothesis, arise by a simple vegetative asexual reproduction of the microspheric parent, many considerations seemed to indicate the probability that the microsphere, the initial chamber of the microspheric form, arose by the conjugation of zoospores. In addition to the general probability of the occurrence of a sexual stage somewhere in the life-history, the sizes of zoospore and microsphere fitted in with the view that the latter might be formed by the coalescence of two of the former. Again, the fact of the rarity of the microspheric form in comparison with the megalospheric was comprehensible, on the supposition that, to be able to conjugate, the zoospores must be of different parentage. The point remained, however, a matter of inference until three years ago, when Schaudinn published an account of the processes that he had observed,' turning inference into certainty. Premising that chromidia is the name applied to the fragments of staining material distributed in the protoplasm, I will quote the passage :

2

"With the onset of the cold part of the year I observed that many large Polystomellas in a vessel were nearly approaching the formation of flagellated spores-that is, that most of the examples which I fixed and stained presented already the complete filling with chromidia, and others had even formed the spore-nuclei. I now took out at random a large number, and, breaking the shells, squeezed out the plasma under a coverslip. In the specimens which had already formed spore nuclei the masses of plasma did not die, but the spores developed quite normally and "swarmed " apart. I was thus not only able to follow clearly with an immersion lens the twicerepeated division of the vesicular nuclei, which occurs very rapidly, but was able repeatedly to observe directly the conjugation of the swarm-cells. The reason that I had not succeeded earlier in this latter, though I had often observed the formation of swarm-cells, is that conjugation only occurs between those arising from separate individuals. I proceeded now as in fertilisation experiments with the eggs of sea-urchins; that is, I crushed a great number of large Polystomellas in sea-water, sucked up the expressed plasma in a capillary tube, stirred it about on the coverglass of a moist chamber, and then had the joy of witnessing many conjugations. The swarm-cells have, as previously stated, two flagella, and a similar wobbling motion to those of Hyalopus which I have minutely described; they conjugate in pairs, and cast off their flagella as in Trichosphærium. The karyokinesis occurs very slowly (5-6 hours). When it is finished the nucleus of the zygote soon divides by direct division, and the typical growth begins, with formation of a shell. I have cultivated the young microspheric individuals in a moist chamber as far as the five-chambered stage, when they died, probably from want of nourishment. In most cases the nucleus had

repeatedly divided. From these small, many-nucleated microspheric individuals the youngest many-chambered stage described in my earlier publications directly proceeds, so that the life-cycle of Polystomella is now complete.'

We are then, at last, able to give with confidence an answer to the question-What is the significance of the phenomenon of dimorphism in the Foraminifera? The answer is, It results from the occurrence of two modes of reproduction in the life-history, sexual and asexual. The megalospheric form is the product of asexual reproduction, the microspheric form arises from the conjugation of two similar zoospores, produced by individuals of the megalospheric form.

In the life-histories of Foraminifera belonging to other families-though not, So far as I am aware, in the Nummulitidæ, to which Polystomella belongs-there is 1 "Untersuchungen üb. d. Fortpflanzung einiger Rhizopoden," Arb, a. d. Kais. Gesundheitsamte, Bd. xix. Heft 3, 1903.

2 I have translated the word "Kopulation" as "conjugation," which in its biological usage describes the nature of the process more accurate'y than the English equivalent.

clear evidence that the members of the megalospheric generation do not always end their existence by the production of zoospores. The protoplasm may emerge from the shells and break up into a brood of megalospheres, as in the reproduction of the microspheric form. In such Foraminifera, therefore, we have to conclude that the megalospheric phase may be repeated in the life-history, and that there may be a succession of megalospheric forms before the sexual stage recurs in the life-cycle. Such a repetition of the asexual mode of reproduction is a common phenomenon in the life-histories of other groups of Protozoa.

In the great majority of cases the size of the megalo sphere is much larger than that of the microsphere, and the two forms are thus easily distinguished. There are, however, species (e.g. Peneroplis, Discorbina globularis) in which the range of variation of the small megalospheres overlaps that of the microspheres, and we have to rely on other characters for discrimination of the two forms.

We must not, however, too hastily apply these results to all the organisms included among the Foraminifera. Wherever there is dimorphism, as expressed in the sizes of the initial chambers, it is clear evidence of the occurrence in the life-history of the sexual and asexual modes of reproduction; and this applies to a wide range of existing species and to fossil forms as far back as the Palaeozoic period. The pelagic Foraminifera present a curious and interesting problem in the fact that their initial chambers are, at least in the great majority of cases, of uniformly small size, a condition which I suspect to depend on their peculiar mode of life. Again, in the simpler groups (Gromiidæ and Astrorhizida) the covering appears, in many cases at least, to expand with the growing protoplasm, so that the evidence of their initial condition is not preserved in the shells. In these cases also we have to seek for evidence of the course of the life-history in nuclear and other characters.

Review of Nuclear Characters.

Turning now to the nuclear changes which are found in Polystomella, there are many features which are worthy of attention. In their feeding, locomotion, and the mode of forming the shell, in fact in all that concerns their vegetative existence, the megalospheric and microspheric forms are, so far as I am aware, exactly alike; yet in one the economy is dominated by a single nucleus, and in the other by many. Richard Hertwig has compared a uninucleate organism, whether a whole protozoon or 3 metazoan cell, to an absolute monarchy, and the multinucleate organism to an oligarchy, in which the rulers though many, perform identical functions. In the lifehistory of Polystomella the apparently revolutionary change in government occurs at each reproductive phase, yet the internal and external relations of the State, as far at least as its vegetative life goes, appear to remain unaltered. Why the nucleus of the microspheric form should divide up into a number of daughter nuclei, while that of the megalospheric form remains single, is, to me at least, entirely obscure.

The separation of portions of the chromatic substance of the nuclei, in both forms of the species, and the ultmate resolution of the whole of it into such shreds, dispersed through the protoplasm, appeared at first a puzzling and obscure phenomenon. In metazoan cells, which are advancing to the formation of the reproductive elements the nuclear divisions occur in regular succession, and the nucleus of a germ-cell may be regarded as the daughter nucleus, granddaughter, great-granddaughter, and so forth. of some other nucleus which went before it. The aphorism omnis nucleus e nucleo appears to hold good for the metazoa, but how does it find its application in the case We are considering? Is there any recognition of the hereditary principle when the change of government of our State occurs? Light has recently come on this obscure phenomenon, and, as usual, by the results obtained in other groups of Protozoa. In the introductory essay, “Die Protozoen und die Zelltheorie," which he contributed to the first number of Schaudinn's "Archiv " Richard Hert wig drew attention to morphological elements of the protozoan body, distinct from the protoplasm on the one

und and from the formed nucleus on the other, and applied to them the name chromidia. They consist of stops of granules or branched strands of a substance staining with the same reagents as the chromatin of the ucieus. In Actinosphærium, in which Hertwig first recogaised them, they are normally present in the protoplasm, but their number is increased in particular states of the ody in relation to metabolism, as by over-feeding, but also, it was found, by starvation. The chromidia are rived from the nuclei, and indeed in certain circumstances the nuclei may completely resolve themselves into chromidia. A structure present in the body of many shelled Rhizopods, and regarded by Hertwig as of the same nature as the chromidia, is the chromidial net. In Arcella this bes in the peripheral parts of the disc-like body, and sends reticulate processes into the rest of the protoplasm. Like the chromidia it stains with chromatin stains. Hertwig concludes that in Arcella the two or three nuclei originally present may, in a certain phase of the lifetastory, completely disappear, and that in that case nuclei are formed afresh by the aggregation of chromatin material bout new foci in the chromidial net. A similar chrodial net was described by Hertwig in Echinopyxis. In the following year Schaudinn pointed out that the chromidia and chromidial net of Hertwig were comparable with the strands of staining substance which had been described in the Foraminifera. In tracing out the very nteresting life-history of Centropyxis he showed that, as in the Foraminifera, the nuclei of the gametes are derived from the chromidial net, while here also the vegetative nucleus disappears. Comparable structures were also shown to exist in Chlamydophrys, a species of Amœba, and in Entamoeba. Schaudinn found that in all the cases investigated by him the nuclei of the gametes are derived from the chromidia, whether diffused or united into a reticulum, and concluded that the chromidia are in fact the substance of the nuclei of the sexual cells. He also instituted H very Enlightening comparison with the Intusoria, the macronucleus of which, formed at the division of the zygote nucleus and disintegrating prior to ronjugation, he compared with the vegetative nucleus of the Rhizopoda, while the micronucleus finds its homologue in the more or less dispersed chromidia.

3

By this comparison a number of previously isolated phenomena fall into line. The nuclear apparatus of the Infusoria, differentiated into vegetative and reproductive portions, finds, though not an explanation, at least a parallel in other groups of Protozoa. The scattered hru midia of the Foraminifera are thus connected with the chromidial nets of monothalamous Rhizopods, which present various degrees of compactness, and through them with the definitely rounded Infusorian micronuclei. involved streaming movements which precede the separation of the protoplasm of the microspheric parent into the megalospheric brood we may recognise a process of equal distribution of the minutely divided chromidia through all parts of the mass which is about to divide, leading to their transmission in equal portions among the offspring.

In the

The fact that in the Foraminifera, at any rate, the chromidia are directly derived from the vegetative nuclei, though they increase in size independently, is at least some acknowledgment of the hereditary principle in the transmission of nuclear material, though we have at present no evidence whatever to show that the foci about which they gather to form the nuclei of the megalospheres or the mother nuclei of the zoospores are in any way derived from preexisting nuclei.

Though light appears ahead, it seems to me that we are not yet at liberty to consider ourselves out of the wood. The comparison of chromidia with infusorian micronuclei has brought us a long way from Hertwig's original observations in Actinosphærium of the dependence of the formation of the chromidia on states of metabolism; moreover, IR. Hertwig. "Ueb. Encystierung u. Kernvermehrung bei Arcella vulgaris, Kupffer's Festschrift. 1800.

Untersuchungen üb. d. Fortpflanzung einiger Rhizopoden," Arb, aus d. Kais. Gerundkeitsamte, Bd. xix... 190%.

Calkins in his very interesting observations on Amoeba proteus also found that the chromídium-like bodies are derived from the vegetative nuclei. See his paper. "Evidences of a Sexual-cycle in the Life-history of Amoeba proti ME. A. f. Protistenkunde, Ed. v. H. (1954).

no evidence has as yet been found that in Actinosphærium the gametic nuclei are formed from chromidia.

In comparing the abundant deeply-staining chromidia of the Foraminifera with the Infusorian micronucleus, so poor in chromatin, Schaudinn ascribes the difference to the fact that in the former, as in Rhizopods in general, the formation of the brood (of zoospores) occurs by simultaneous multiple fission, and is connected with the act of fertilisation, so that sufficient chromatin to provide for the nuclear equipment of each of the thousands of zoospores must be ready in the parent as it approaches the reproductive stage. In the Infusoria, on the other hand, where the gametes are the ultimate product of a succession of binary fissions there is never the occasion, at any one time, for so large a store of chromatin in the body. While admitting that there is much force in this explanation, we may notice that in Polystomella the formation of the chromidia begins early in the growth of the microspheric individuals, and they are in my experience very prominently present in full-grown specimens of this generation, although the sexual nuclei are not formed until the next or megalospheric generation has reached maturity. would appear, therefore, that in Polystomella the chromidia are associated with the formation of the nuclei of the reproductive elements, whether these do or do not engage in conjugation.

It

Goldschmidt, in a very capable review of our knowledge of chromidia, is inclined, on the ground of the apparent difference in relation to the life of the organism between the structures so called by Hertwig, in Actinosphærium, and the chromidial nets and strands of Rhizopods, to the view that two physiologically distinct elements have assumed a morphological similarity and mode of origin. While retaining the name chromidia for the former, he distinguishes the latter under the name Sporetia. It is, however, perhaps somewhat early at present to insist on this distinction. Hertwig's essay has already been most fruitful in results, and we cannot doubt that the nature of the chromidia will be further elucidated now that attention has been directed to them.

The relation in size between the microspheric parent and
the members of the megalospheric brood.
There is one other point to which, before concluding,
I wish to invite your attention.

In the course of the discussions on the significance of the occurrence of nummulites in pairs, objection was taken to the view that the members of the pair belonged to the same species on the ground that solitary forms --megalospheric or microspheric, unaccompanied by the usually associated sister form-occurred in certain localities. De la Harpe himself, having at first urged this objection, withdrew it; but it is still entertained by some palæontologists, and made the ground for maintaining the view that the members of a pair are specifically distinct.

On looking into the matter I found that two out of the three species of Nummulites which occur in the Brackle sham and Barton beds in the Hampshire basin were only known, SO far as published descriptions went, in the micromegalospheric form, although the corresponding spheric forms had been found associated with these megalospheric forms on the Continent. It therefore seemed worth while to examine the English beds to see whether they might lend any support to the view I have mentioned The three English species are the following:

Nummulites laevigatus (Brug.), megalospheric form "N. Lamarcki, d'Arch."

N. variolarius (Lamk.), microscopic form "N. Heberti, d'Arch."

N. Orbignyi (Galeotti), megalospheric form "N. wemmelensis, d. 1. H. and v. d. Br., var. elegans, Sow." In N. laevigatus the microspheric form far exceeds the megalospheric, in the size attained by the full-grown tests, 1 I have here considerably expanded what I take to be Schaudinn's meaning. His words are (2.c. r. 553): "Die Chromidien (of Polystomella) entsprechen den in der Ein- oder Mehrzahl vorhandenen Geschlechtskernen oder Mikror uclei der Infusorien. Der Unterschied besteht nur darin, dass wegen der Verknüpfung der Brutbildung mit den Kopulationsvorgangen die Geschlechtsker substanz bei Polystonella in viel grosseren Quantitäten vorhanden ist, als bei den Infusorien.

2 Die Chromidien der Protozoen Arch. f. Protistenkunde. Bd. v.. 1 (1954), p. 126.

as we have seen to be usually the case with nummulites; but in the other two species the size attained by the two forms is approximately the same. Hence there is in them no external indication of dimorphism, and it is necessary to grind down the little shells to expose the initial chambers in section before they can be referred to one form or the other. The results of the investigation are fully set forth elsewhere, and I need only say here that on proceeding in this manner with these two species, after grinding down a number of examples which proved to belong to the commoner megalospheric form, I came in each, as I fully expected I should, on examples of the microspheric forms. The English beds, therefore, offer no support to the view that one or other of the forms of a species may occur solitary.

On examining sections of the two forms, megalospheric and microspheric, in the three species, a further point of interest presented itself, namely, that the megalosphere, the initial chamber of the megalospheric form of N. laevigatus, was much larger in proportion to the size of the megalospheric shell than the megalospheres of N. variolarius or N. Orbignyi. I was, therefore, led to examine the proportion in a larger number of forms, and the fine series of nummulites contained in the collection presented by Dr. H. B. Brady to the University of Cambridge gave me the opportunity of doing so on ten species or varieties.3

In N. complanatus the microspheric form attains a diameter of about 2 inches (51 mm.), the megalospheric form a diameter of 5.9 mm. In N. variolarius the microspheric form has a diameter of about 1.92 mm. and the megalospheric form of about 1.8 mm.

The result of careful measurement was to show that the volume of the megalosphere is, within narrow limits, proportional to the volume of protoplasm contained, not in the whole megalospheric, but in the whole microspheric test. In other words, and in the light of our knowledge of the life-history of the dimorphic Foraminifera, the volume of each of the individual members of a brood of megalospheric young is in Nummulites proportional to the bulk of the protoplasm of the microspheric parent out of which they are formed. In Hertwig's essay, above quoted, it is pointed out (p. 30) that in functional cells (not eggs) there is a definite proportion between the mass of a protoplasmic body and the mass of nuclear substance contained in it. If we apply this to the result attained for Nummulites it would appear that the mass both of the protoplasm and its contained nuclear material are in this asexual mode of reproduction proportional to the whole bulk of the protoplasm out of which they are formed. would appear to follow that among Nummulites the number of the members of the brood in the asexual mode of reproduction ought to be approximately the same in all species. In the sexual mode of reproduction no such relation holds, for the microsphere in N. gizehensis, the microspheric form of which attains a diameter of 23.7 mm., is hardly larger than that of N. variolarius, in which the diameter of this form is, as we have seen, 1.92 mm.

It

44

In addition to the structural and other characters, binding the members of a pair" of Nummulites together, which led De la Harpe to conclude that they belong to the same zoological group, we may now therefore add another -the ratio in volume between the megalosphere of one and the protoplasmic contents of the whole shell of the other.

It would be interesting to find how far this proportion holds good in other genera of Foraminifera. I do not know of any phenomenon precisely comparable with it elsewhere, but the result is so definite that it would appear to be the expression of a general principle.

In conclusion, I may call attention to the differenc presented by the species of the genus Nummulites in the relative length of life (as indicated by size) of their sexually and asexually produced forms. In N. variolarius the lifecycle is apparently equally divided between the two, while in N. complanatus the small megalospheric form ("N Tchihatcheffi") is almost as much dwarfed by the gigantic microspheric form as, in the life-history of a fern, the prothallus is by a member of the sporophytic generation.

THE King has approved of the appointment of Admiral Sir Arthur Dalrymple Fanshawe, K.C.B., as president of the Royal Naval College, Greenwich, in succession to Sir Robert Harris, K.C.B., K.C.M.G.

SIR WILLIAM THOMSON has been appointed by the Chief Secretary for Ireland inspector of schools of anatomy for the provinces of Connaught, Ulster, and Leinster, in the place of Dr. W. J. Martin, deceased.

AT Lehigh University Messrs. P. A. Lambert and A. E. Meake have been appointed professors of mathematics and at the same university Mr. J. D. Irving has been elected to a professorship in geology.

DR. D. NOËL PATON, superintendent of the laborators of the Royal College of Physicians, Edinburgh, has bee appointed regius professor of physiology in the University of Glasgow in succession to Prof. J. G. M'Kendryk F.R.S., resigned.

PROF. WM. H. HOBBS, of the University of Wisconsin, has been appointed successor to the late Prof. Israel C Russell in the professorship of geology in the University of Michigan. Prof. Hobbs, who is at present in Euros. will leave for America to take up his new duties on August 25.

THE eleventh annual examination in the science and practice of dairying for the national diploma of the National Agricultural Examination Board will take plac® at the Midland Agricultural and Dairy College, Kingstar Derby, from September 24-27 for English students, and at the Dairy School, Kilmarnock, from October 1-3 Scottish students. All applications must be sent in by, 2o latest, August 31. The subjects of examination are general management of a dairy farm, the manageinert a dairy, chemistry and bacteriology, practical skill in dair work, and capacity for imparting instructions to otherForms of entry and copies of the regulations may Society, or from the secretary of the Highland and A obtained from the secretary of the Royal Agricultur cultural Society.

SOCIETIES AND ACADEMIES.

LONDON.

Royal Society, May 31.-"The Affinity Constants of Amphoteric Electrolytes.' I. Methyl Derivatives of Para-amino-benzoic Acid and of Glycine," by John Johnston. II. "Methyl Derivatives of Ortho- and Metaamino-benzoic Acids." by A. C. Cumming. III." Methylated Amino-acids," by James Walker.

The object of the present series of papers was to determine the influence of the substitution of the methyl group in NH, on the acidic and basic dissociation constants of amino-acids. The methods employed for the determination of the dissociation constants were for the most part hydrolytic, i.e. the degree of hydrolysis in aqueous solution of both types of salts of the amino-acids was estimated at given dilutions. For the basic constant methyl acetate catalysis, Löwenherz's solubility method and Farmer and Warth's distribution method employed. In addition to these methods, the delicate diazo-acetic ester catalysis of Bredig and Fraenkel was used in a few instances. For the acidic constant, the electrical conductivity and Shields's saponification method were utilised.

were

Each substance investigated was subjected to careful purification, and many new methods were devised for the preparation of the methyl derivatives required. It may be noted that the monomethyl-meta-amino-benzoic acid described by Griess is a mixture of the monomethyl and dimethyl derivatives which it is practically impossible to separate by recrystallisation.

A comparison of the acidic and basic constants of the various substances examined showed that they were in general accordance with the following scheme. The primary influence of the substitution of methyl for hydrogen in the amino group is to raise the basic and diminish the acidic constant, the effect in both cases being, however, only slight. This primary influence is usually obscured by greater secondary influences due to stereochemical changes. These changes may exert their influence (1) by mere approximation of the active groups; (2) by change in degree If hydration of the basic group; (3) by ring-formation. In the case of ring-formation the acidic constant is ciminished, speaking in general terms, proportionally to the extent to which the ring-formation has taken place. The basic constant, on the other hand, need not be so riminished, because the basic constant in the bodies investigated is principally a function of the hydration constant of the basic group, and the degree of hydration may not be diminished by increased ring-formation. A comparison of the basic constants of the amino-acids with those of their methyl esters affords information regarding the reciprocal stereochemical influence of the active groups. When there is little stereochemical influence the basic constant of the acid is nearly equal to that of the ester. When the stereochemical influence is marked the basic constant of the acid is much less than that of the ester. The following table of the constants of ortho-aminobenzoic acid and of para-amino-benzoic acid and their ethyl derivatives may serve as illustrations. In the ortho series stereochemical influences are apparent, in the para ries they are nearly absent.

value, notwithstanding the extensive ring-formation, owing to the very high constant of the quaternary basic group, which cannot suffer dehydration except through ringformation. The quaternary basic group of the betaine esters was proved to have basic properties comparable in strength with those of the caustic alkalies.

June 21. On the Distribution of Radium in the Earth's Crust. By the Hon. R. J. Strutt, F.R.S.

In a paper read before the society on April 5, the author gave determinations of the quantity of radium in igneous rocks. Similar data for sedimentary deposits will now be given to complete the survey of the radium content of the earth's crust.

The results for sedimentary rocks are given in Table I.

On comparing these figures with those given in the former paper for igneous rocks (Roy. Soc. Proc., vol. Ixxvii., A, p. 479, last column but one of the table), it will be observed that the average radium content of sedimentary deposits does not differ appreciably from that of igneous rocks. This is what might be expected on the received view that sedimentary rocks derive their material from the disintegration of igneous ones.

The author has examined a number of specimens of rock-forming minerals for radium. The results are given in Table II. In some cases the quantity of material taken TABLE II.

Ortho Series.

Esterk 1012

Sphene

1'4

13

Apatite

0'46...

0'9

33

Apatite

Magnet Cove,
Arkansas
?
Sweden
California ...

197 10-12

0'00023

0.28

60

White felspar... White mica Brown mica Brown mica White quartz Rutile Ilmenite ...

Nellore, India...

20

10-12 10-1 0'6 ΙΟ

-12

Nellore, India.

1Ο

Deccan

1Ο

ΙΟ

I

?

10

Nellore, India... 30

I

Ni