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Three hundred and sixty-eighth meeting.
September 14, 1852. — Monthly Meeting. The President in the chair.
Dr. M. Wyman communicated to the Academy the results of some experiments upon animals, with a fluid obtained by distilling water and fusel-oil from chloride of lime, in the usual way of manufacturing chloroform, substituting only fusel-oil for alcohol.
A large, strong rat was placed in a quart “beaker-glass” with its mouth upward, and covered with a glass plate. A piece of cotton, well moistened with the fusel-oil compound, was placed in the vessel. In five minutes, no effect being produced, an equal quantity of the compound was poured upon the cotton; in thirteen seconds, another and equal quantity added. In thirty minutes the rat was washing its face with its paws, and licking its body; in forty minutes, it was apparently well. Fresh air was admitted into the vessel at each addition of fusel-oil compound.
Half a fluid drachm of chloroform was placed in the vessel. In one minute and five secouds the rat had rolled upon its side ; in two minutes it was motionless ; in three minutes and fifteen seconds it was dead.
A young kitten, exposed to the compound nineteen minutes, was not injured. It sucked the mother immediately after. Another kitten, of the same litter, was exposed in a similar vessel to the vapor of chloroform. In two minutes it became insensible, and was removed from the vessel ; in two minutes twenty-three seconds it partially recovered, and was returned to the vessel ; in eight minutes it dropped again; in eight minutes fifty seconds it was gasping ; in nine minutes it was again insensible. It was removed from the vessel, and finally recovered.
Several other experiments were tried upon kittens, and upon frogs, both with the fusel-oil compound alone and mixed with the vapor of chloroform, and the conclusion was inevitable that the vapor of the fusel-oil compound was not alone injurious to animal life, and that mixture with the vapor of chloroform did not modify its effects upon the animals exposed to it.
The vapor of the fusel-oil compound was subsequently inhaled steadily by Dr. Wyman twelve minutes, without any sensible effects. Chloroform produced a decided effect in two minutes.
The fusel-oil compound is vaporizable at a much higher temperature than chloroform, and when a mixture of the two is exposed to the air, the chloroform evaporates, leaving the fusel-oil compound behind.
The fusel-oil compound, therefore, is not the cause of the occasional fatal effects of chloroform, as has been alleged.
Dr. Wyman stated that these experiments had been made in 'consequence of a statement which had been published concerning experiments on the same subject, said to have been recently made, with very different results.
Dr. W. I. Burnett presented a paper upon the Formation and Function of the Allantois. After alluding to the difficulties attending the study of this subject, and to the various opinions entertained by different embryologists as to its origin and function, he proceeded to state the results of his own observations.
“ These were made upon mammals, birds, and reptiles. But as in these three classes there are no essential differences, the phases of formation in birds, which are most convenient for study, may be described as exponents of the whole.
“In the chick the allantois first appears at about the sixtieth hour of incubation. At this early period, the abdominal plates inclose no organs, except the heart, with its ascending and descending aortas, and the Wolffian bodies. There is then no trace of an alimentary canal, or any of its appendages.
“ At this early period, the Wolffian bodies consist of two tubes, one on each side of the vertebral column, running from the region of the heart to the caudal extremity.
“ From each of these tubes there then project short digitations, which are to be the future uriniferous tubes of this organ ; the original tube becoming the duct of them all in each organ.
“These ducts pass down to the last caudal vertebræ, over which they turn and come together; at their point of junction appears a small vesicle, the expansion of their combined extremities. This vesicle a minute sphere, and scarcely to be distinguished from the extremities of the ducts themselves - is the allantois in its earliest condition.
- At first its walls are extremely thin, being of a most delicate membrane ; but as its size increases, cells appear upon its inner surface, and at last a basement membrane is perceived, covered with epithelial cells. All these formative changes have taken place beneath the investing membrane of the whole embryo, and directly at the point of the branching of the two umbilical arteries.
“ As the vesicle expands, it pushes out, first, the branches of these arteries which rest upon it, and by anastomosis form a network ; sec. ond, a hood of the membrane investing the whole embryo. In less than a day after this, when the vesicle has attained the diameter of one sixteenth of an inch, the network of vessels united in the hood of the investing membrane has so increased, that it seems to form the vesicle proper, the original membrane being entirely masked. At this period the allantois bas very much the aspect of a diverticulum of the investing membrane of the embryo, and to this perhaps is due the opinion of Coste as to its origin.
“ After this it increases rapidly, the spherical vesicle becoming flask-shaped, and extending out quite beyond the caudal vertebræ, around which it passes to reach the dorsal surface of the embryo. Here it meets the amnion, with the membranes of which it partly blends, and in this way serves to conduct to it the umbilical vessels.
“ Such is its mode of formation. Its functional relations are equal. ly interesting.
“I would remark, in the first place, that the Wolffian bodies are truly depurating organs of the blood ; in fact, are the temporary kidneys of the embryo. We have seen that the allantois appears as the bulbous termination of their combined ducts, at a very early period of embryonic life. But it does not arise until the Wolffian bodies have attained a functional power; that is, until uriniferous tubes are formed having direct relations with the bloodvessels. Indeed, the allantois, as the receptacular termination of the ducts of the Wolffian bodies, is not forined until a urinary secretion is produced.
“ These facts, joined with the very significant one, that Jacobson found uric acid in the liquid of the allantois at a very early period, seem clearly to indicate that the primary physiological function of the allantois is to serve as a urinary bladder. This office it serves during the whole period of the persistence of the Wolffian bodies, or until the involution of its neck with the intestine changes the anatomical relations of its ducts. Its subsequent function, however, is different, and of a more important character.
“ In the mammalian Vertebrata, the embryo forms vascular and nutritive connections with the mother at so early a period that the new being exists but for a little time under independent conditions. As soon as there is direct vascular connection by means of the chorion, the independent life of the embryo ceases, and its nutrition, respiration, and other necessary functions, are performed by the mother.
“But until this period, the allantois exercises a most important function, namely, that of respiration. Its surface is covered with a close network of bloodvessels, closely resembling the pulmonary structure of the lower vertebrates.
“In the embryos of the ox and goat, so young that no vascular connection had taken place with the mother, I have seen the provisional blood-corpuscles (which are at first only simple epithelial cells) become oxygenated, acquiring a red color, from circulating in these vessels.
“ The allantois is then probably a temporary pulmonary organ; the form of respiration being of the lowest order, and quite in character with the condition of the embryo, that is, aquatic.
“ While performing this function it extends to the chorion, blends with its membranes, and its vessels pass over to it (the chorion.) In this way the independent relations of the embryo cease, and the Al. lantois as a distinct organ entirely disappears.
“In the oviparous Vertebrata, the embryonic conditions are different. Of these the birds and true reptiles alone have an allantois and amnion. Here the functional importance of the allantois appears greater than in the division just described.
“ Undoubtedly it serves here, as in Mammalia, as a urinary bladder during its earliest conditions. But its respiratory function soon appears prominent. It increases rapidly, and ultimately envelops the embryo, yolk-sac, and amnion. With these relations it performs the
function of respiration by two methods : first, by means of the oxygen of the liquid in its membranes; and second, by bringing a dense network of vessels in contact with the air, which passes through the pores of the shell and surrounds the whole formation. In the latter stages of the embryonic development, it is probable that this second method is most efficient, because most direct.
“ From these facts we may conclude that the allantois is, anatomi. cally, an appendix of the Wolffian bodies, and not of the intestinal canal, as has been supposed ; that its subsequent connection with the intestine is produced by an involution of the membranes of this last around the peduncle of the former. But whether this connection is ever a direct and tubular one, I have been unable to determine.
“ Physiologically it is at first the receptacle of the urinary secretion of the Wolffian bodies ; but afterwards and ultimately it is a respiratory organ.
“ These conclusions I have arrived at from direct studies, and it will now be interesting to see how they agree with the general facts of the embryonic development of Vertebrata.
" It is evident that, if the allantois is an appendix of the Wolffian bodies, it would be expected to be met with only in those classes where these bodies are found. In other words, wherever we find an allantois, there ought we to find Wolffian bodies, and vice versa.
“ These relations, I believe, are true. Thus in mammals, birds, and the true reptiles, we find invariably Wolffian bodies and an allan. tois. While in the lower oviparous Vertebrata, as in the Amphibia and fishes, there are neither Wolffian bodies nor an allantois.*
“ Thus it would appear that the views here advanced of the origin and nature of the allantois, are supported by the general embryological relations of all the classes of Vertebrata.”
Professor Agassiz followed with some remarks. After highly complimenting Dr. Burnett's paper, he stated that circumstances had incidentally led him to investigations upon
* “A remark is here necessary concerning the reputed Wolffian bodies of Amphibia. As is well known, these bodies were first described by Maller more than twenty years since. According to his own description, they differ in almost every respect from the Wolffian bodies of the higher classes.
“After much examination during this last summer, I have failed to recognize in their structure and general relations the characteristics of the Wolffian bodies, and have therefore ventured to rank the Amphibia, in this respect, with the fishes."