5. On the Production of Heat in Hibernating Animals. By RAPHAEL DUBOIS, Professor of Physiology in the University of Lyons.

For several years the author has investigated the production of heat in the marmot in order to find out what part of the nervous system is essential for the rapid production of heat which takes place when the animal wakes up from its winter sleep.

Section of the spinal cord at the level of the fourth cervical vertebra prevents the animal from raising its temperature. Destruction of the grey substance of the brain produces a similar effect. If the section of the spinal cord be made at the level of the seventh cervical vertebra the animal grows warm slowly and incompletely; but if the operation be performed between the fourth and fifth dorsal vertebræ, then the curve of the rise of temperature presents the normal form. There is therefore a limited portion of the cord, between the fourth cervical and the first dorsal vertebræ, through which pass the centripetal or centrifugal, or both, impulses, placing the cortex of the cerebral hemispheres in communication with the rest of the organism. The pathway is through the grey substance of the spinal cord, for section of the antero-lateral or of the posterior columns does not prevent the animal from producing heat, whereas destruction of the grey matter in this limited portion of the cord produces the same effect as total section. This operation produces immediate loss of the power of movement and conscious sensibility in the greater part of the body; but the absence of the capacity to produce heat must not be attributed to this sensory and motor paralysis, for section a little lower, at the fourth dorsal vertebra, does not change the normal curve of tempera

ture.

The section of the cord at the fourth cervical vertebra abolishes, on the one hand, the contractions of the thoracic muscles, the activity of which is very great during the rewarming and insignificant during the torpor; on the other hand, it cuts off the very important connections of the sympathetic system with the higher centres. If the cervical sympathetic be cut on both sides above the inferior cervical ganglion there is no very marked delay in the production of heat, whereas the rise of temperature is very slow and incomplete when the inferior cervical and the first thoracic ganglia are removed on both sides. These ganglia, however, are only connecting links, for the same result is obtained by section of the two splanchnic nerves or of the branches which pass directly from the abdominal sympathetics to the semilunar ganglia. Extirpation of the semilunar ganglia produces the same result as removal of the inferior cervical and first thoracic ganglia.

Experiments show that it is by acting upon the portal system that the sympathetic shares in the general process of heat production. It regulates the quantity and pressure of the blood which flows to the liver, and in this manner the production of heat in the liver and the transformation of glycogen into sugar, to be utilised for combustion when the animal awakes. The thoracic muscles become exceedingly active when the animal awakes, and thus require more glycogen or other combustible material for their contraction.

A full account of this research will shortly be published in 'Les Annales de l'Université de Lyon.'

6. On 'Pigeons' Milk.' By E. WAYMOUTH REID, Professor of Physiology in University College, Dundee.

John Hunter (1786) discovered the fact that pigeons feed their young for some days after hatching upon a substance resembling the curd of milk, and formed in the lateral pouches of the crop of both cock and hen. This method of feeding is as yet only known in this tribe of birds.

Claude Bernard (1859) studied the nature of the substance, and found that

microscopically it consisted of masses of the epithelial scales of the crop mucosa. loaded with fat globules. An analysis made for Bernard by Leconte gave

No sugar was present-a fact noted also by Hunter.

Hasse (1865) and more recently Max Teichmann (1889) have also written on the subject from the histological point of view.

The lateral pouches of the crop of the non-breeding pigeon are not glandular; the epithelium is stratified and free from fat, the submucosa provided with small vascular papillæ.

The change in the crop membrane necessary for the formation of the 'milk' commences during the incubation of the eggs, and though not visible to the naked eye till two or three days before hatching, makes itself evident by the appearance of fat-droplets in the cells ten days before this event. The main change consists in a great thickening of the epithelium, accompanied by rugose folding with reticulation, while at the same time the structure becomes enormously vascular and capillaries penetrate the epithelial layers (Hasse and Teichmann).

Small pellets of curd-like matter form in the pits of the reticulated surface, and as soon as the young are hatched these are transferred by the parents to the crops of the squabs,' often to the extent of 40 per cent. of the weight of the bodies of the young.

In its histological features the process of formation of the milk' resembles more closely that of the formation of sebum than of milk, for whole masses of fat-holding cells are cast off from the walls of the pits in the membrane; yet, unlike the sebaceous process, the nuclei of the cells persist.

Interpapillary involutions, then, of the thickened stratified epithelium of the crop act as sebaceous glands during the period of formation of the 'milk.'

This period lasts for from seven to nine days after hatching, and the maximum of activity is reached about the second day after hatching.

The young are fed almost exclusively on this substance for the first three days, though a few crushed grains are also supplied by the parents. The parents appear to crush the grains at first, though later they are supplied whole. This fact is accounted for by the condition of the gizzard membrane of the early 'squab,' for the horny secretion of the tubular glands of the mucosa takes some days to con solidate. No digestive ferments are supplied by the parents along with the 'milk," and the proventriculus of the young'squab' pigeon, even at twelve hours, is rich in proteolytic ferment, its glycerine extract digesting fibrin with ease. The crops of neither adult (breeding or non-breeding) nor young birds form any amylolytic or proteolytic ferment; in both cases, however, multitudes of bacteria and cocci are present, and the acidity of the contents (reaction of Uffelmann, but no reaction with phloroglucin and vanillin) is probably due to lactic fermentation. The pancreas of the squab' is capable of digesting starch at the time of hatching.

In the 'squab the cell bodies of the 'milk' are dissolved off by the secretion of the proventriculus, and the fat set free in the gut is found in the cells of the villi, and also in the leucocytes of the blood. The fæces of the 'squab' are fat-free, though at an early stage they contain considerable proteid.

Though sugar is undoubtedly absent from the milk,' a young'squab' pigeon before it has received any food contains sugar. In one case a triple alcoholic extract of a minced and finally pulverised squab' yielded over 2 per cent. of its body weight of reducing sugar, while a subsequent triple aqueous extract gave 16 per cent. of the body weight of an amylose yielding sugar on boiling with dilute sulphuric acid. This amylose struck no colour with iodine, and attempts to demonstrate glycogen in the bodies of unfed squab' pigeons have failed, though th pectoral muscles of adult birds are very rich in this substance.

5 in

as the

As regards the proteids of the milk,' extracts with normal saline by trituration and digestion with thymol at 40° C. show absence of fsory. proteoses, and peptones; presence of globulin and of caseinogen (cle-sory. The

with and without calcic chloride). The chief proteid, however, appears to be of the nature of nucleo-albumin (Halliburton's sodic-chloride method). Mucin is present in variable amount, and originates from the glands of the gullet below the crop. These glands enlarge and become more active during the feeding of the young.

The young pigeon is, then, fed at first upon a highly nutritious food, whose solids consist in the main of nucleo-albumin and fat. The explanation of this peculiar process lies in all probability in the fact that since pigeons rean so many broods in a season the young must be brought forward faster than could result from mere grain feeding, and hence a magnificently nutrient diet is supplied. When a cock or hen in milk' is separated from the young the involution of the crop changes occurs with great rapidity, for within twenty-four hours the temporary 'sebaceous glands' are loosened and cast off, the hypertrophied papillæ which lie between them being subsequently reduced. Such birds swallow their own 'milk;' their villi contain more fat than normal birds, and fatty leucocytes are seen in abundance in the blood.

Some days, however, after separation, though the gross changes in the crop membrane have disappeared, fatty cells are found in the epithelium.

The 'milk' in the crops of such separated birds is also in finer particles than normal and poorer in solid constituents.

A few quantitative analyses, kindly made for me by my colleague Mr. F. J. Hambly, are appended :

% Milk % Solids % Milk % Solids % Milk % Solids % Milk % Solids

7. On the Structure of Striped Muscle. By Professor J. B. HAYCRAFT.

The cross-striping of muscle is due to the form of the fibril and not to its internal structure. The fibril is like a beaded rod, and the striping is the optical expression of this. The proof of this is obtained by stamping moist collodion with a piece of muscle. The collodion stamp preserves the form of the fibrils, and shows identically the same cross-striping to the minutest detail. The stamps and their photographs were demonstrated. In one a fibril had been stamped in which one part alone was in the condition of contraction, and every detail of the striping, both in the relaxed and contracted conditions, was identically reproduced.

TUESDAY, AUGUST 14.

1. A joint meeting with Section A was held to discuss the following Papers days'rofessor Oliver Lodge, F.R.S.

the later-Experiments illustrating Clerk Maxwell's Theory of Light.
as yet only
An Electrical Theory of Vision.
Claude Bei

The following Papers were read :—

2. On a Modification of Golgi's Methods. By OLIVER S. STRONG, of Columbia College, New York.

Golgi's methods may be divided into two principal heads: (1) The sublimate method, consisting essentially of hardening in bichromate of potash followed by immersion in bichloride of mercury. This method need not be further noted here.

(2) The silver methods, consisting of (a) the long, or slow, method, consisting of hardening for about twenty to thirty days in potassium bichromate followed by immersion in a solution of silver nitrate. (6) The rapid method, where the hardening is done in a mixture of bichromate and osmic acid. This is the method, slightly modified, which is so extensively used, and is the method used by Ramón y Cajal. (c) What may be designated the mixed method, or combined method, and consists in hardening first for a few days or a week or so in potassium bichromate, then a day or two in the osmium-bichromate mixture, and finally the immersion in the silver bath.

The rapid method is the best yet discovered for work on the peripheral terminations of nerves and for the embryonic central nervous system. For adult brains it is not so well adapted owing to the poor penetration of the osmic acid, and consequent liability to overharden the periphery while the central portions of even small pieces remain untouched. Moreover, adult brains are not well adapted for the study of the nervous or axis cylinder prolongations of the cells, owing probably to their sheath, so that on such material study by these methods would be chiefly directed to the cell bodies and their protoplasmic expansions. For such purposes the long Golgi method is eminently adapted.

While the long Golgi method avoids the disadvantages, including the expense -no small consideration where such quantities are used-of osmic acid, it has the disadvantage of requiring about a month, besides the uncertainty common to all these methods.

In order to reduce this period of time, and yet to avoid the use of osmic acid, the new method here proposed for the study of adult brains is the use of bichromate of lithium instead of the bichromate of potassium, with the same percentages. I have found that tissues (small pieces) placed in the former reach the favourable stage of hardening for the silver impregnation in the course of one to two days, instead of twenty to thirty days. It passes through this favourable period quite rapidly, but the whole process is reduced to such a short time that it is rendered much less tedious. The pictures yielded by this process, judging from the few made thus far, are certainly fully equal to those prepared by the other methods.

The subsequent treatment is as in the other methods, i.e., the piece of tissue is rinsed in strong alcohol, cut free hand or gummed on a block without any imbedding, and cut with a microtome. The sections are washed in several changes of strong alcohol, cleared in oleum origanum Cretici, washed briefly in xylol, and mounted in dammar or Canada balsam, thinned with xylol, without a cover slip.

It would be interesting to ascertain how well adapted this new hardening reagent would be for preparing the central nervous system for other methods of staining, e.g., the Weigert method.

3. On an Attempt to supply Motor Power to the Muscles of the Larynx from a New Source. By Veterinary-Captain F. SMITH, F.R.C. V.Š., F.I.C., F.R.C.V.Š., Army Veterinary Department, Aldershot.

The subject used in these observations was the horse, the inquiry having in view the possible relief of the respiratory distress so common in this animal as the result of laryngeal paralysis.

The new source of nerve supply was sought for in the spinal accessory. The

recurrent and spinal accessory were exposed and divided, and the proximal end of the accessory was sutured to the distal end of the recurrent.

The only convenient test which could be employed to ascertain what progress the animal was making after the operation was that afforded by galloping it.

In one case, a few months after the above nerves had been united, there was only a slight harshness in the breathing during inspiration, even when the horse was severely pressed;' whereas, unless nerve impulses were passing down the accessory and through the recurrent to the larynx, the animal should have suffered from intense dyspnoea, as the whole of the dilator muscles of one side of the larynx would have been paralysed.

In a second case, the recurrent, before suture to the accessory, was known to have been degenerated for at least two years. This animal continued to have noisy breathing up to the time it was destroyed (twelve months after the operation), but it was unaccompanied by distress.

In the first case only an ordinary post-mortem examination was made to ascertain whether the nerves were united; in the second horse the nerves were stimulated electrically immediately after death, and a careful microscopical examination of the parts made.

On stimulating that portion of the recurrent in connection with the larynx the muscles actively responded; on stimulating the accessory well above the nodule uniting it with the recurrent, the muscles of the larynx again actively responded.

These observations were repeated several times by Professor Delépine, of Manchester (who kindly associated himself with me as an independent observer in the post-mortem examination), and the results are beyond doubt.

The muscles of the larynx of the above case, supplied by the accessoryrecurrent nerve, were smaller and decidedly paler in colour than the healthy ones on the opposite side; on directly stimulating the muscles every portion of them actively responded to a weak current.

Professor Delépine examined the united nerves microscopically, and found in the recurrent between the point of union and the larynx small bundles of medullated nerve fibres and an amount of epi- and peri-neurium larger than normal. The place occupied by the old funiculi was quite distinct, but the nerve fibres occupied only a portion of the spaces thus indicated. The nerve fibres were all of smaller diameter than normal; most of them had a very thin myelin sheath which stained well with osmic acid. Professor Delépine was of opinion from this and the other observations that partial regeneration had certainly taken place, and that regeneration was progressing at the time of death.

By the tests employed it was not possible to say whether co-ordination of the laryngeal muscles occurred, but it is proposed in future observations to examine closely into this subject, and employ the laryngoscope to ascertain whether the impulses to the larynx are sent at the right moment.

At present it would almost appear to be possible to educate a nerve centre to perform a duty it was never intended for.

4. On the Causes and Prevention of Suffocation in Mines. By J. S. HALDANE, M.A., M.D., Lecturer on Physiology, University of Oxford. Evidence was brought forward by the author that most of the deaths caused by colliery xplosions and fires in the workings are due to suffocation, so that a thorough instigation of the subject is of great practical importance.

He concluded that poisoning by carbonic acid is never the cause of death in cases of suffocation by choke-damp, black-damp, or after-damp; that deprivation of oxygen is always the cause in the cases of choke-damp or black-damp, and usually the cause in the case of after-damp, although after-damp, even when much diluted, is sometimes poisonous from the presence in it of products of in