Abstract
BERLIN Physiological Society, June 19.—Dr. J. Munk gave a brief sketch of the different views put forth respecting the formation of fat in the animal body, and then gave a short account of the now almost universally accepted view of Voit, who, on the basis of his very numerous experiments, laid down the doctrine that the fat in the animal body proceeded either from the alimentary fat, or, when this was not sufficient, from the albumen, which on its decomposition yielded products that by synthesis became transformed into fat, while the carbohydrates never yielded material towards the formation of fat in the animal body. Opposition to this doctrine was raised on the side only of agricultural chemists, who, by experiments on swine and geese produced direct demonstration that the deposition of fat was considerably increased by feeding with carbohydrates. In consequence of these experiments Prof. Voit admitted that omnivorous and herbivorous animals might in certain circumstances form fat out of carbo-hydrates; such, however, he maintained, was never the case with carnivorous animals and man; in them all fat was derived from the alimentary fat and the decomposition of albumen, both in his own experiments and in all hitherto published, and the fat was seen to be derivable from these two sources alone, even though only 12 per cent, of the decomposed albumen were taken for the formation of fat, and much more if, according to the theoretic calculations of Herr Henneberg, it was assumed that as much as 51 per cent, of the decomposed albumen might be utilised towards the formation of fat. Seeing now that Prof. Voit admitted that, in the case of omnivorous and herbivorous animals fat was produced from carbo-hydrates, the speaker set himself the task of establishing experimental conditions under which fat might be formed from carbo-hydrates in the case, likewise, of carnivorous animals. For these experiments he selected a dog, completely impoverished it of all fat by means of long fasting, and then gave it an aliment very rich in carbohydrates. The animal required to be young, or otherwise the loss of fat by fasting could not be complete, and if it were desired to obtain certainty respecting the attainment of perfect deprivation of fat, the decomposition of the albumen during the period of fasting would have to be traced by regular determinations of the quantity of azote in the urine and the excrement. Prof. Voit had (as was already known) proved that on account of its readydecomposibility, fat was a protection against the decomposition of albumen; such would necessarily be the case in the fasting organism likewise, and the corporeal fat would necessarily protect the albumen from decomposition. In point oi fact Dr. Munk found in fasting animals that when they were poor in fat the decomposition of albumemslowly abated in correspondence with the ever less abatement of the weight, whereas in the case of mdividuals rich in fat, the nitrogenous secretions in the last period, after the corporeal fat at disposal had been decomposed, did not only not abate, but even increased somewhat. The same cause as that followed by the nitrogenous secretion was also observed in the case of the elimination of sulphur. The exact process of albuminous decomposition during fasting thus offered an indication of the attainment of complete deprivation of fat in the body.The carrying outot the experiments was, however, attended with so many difficulties, that hitherto only one experiment hadsucceeded.It had reference toa large dog of-three to four years old, weighing about 35kilogrammes, which hadbeenmadeto fastforthirty-one days,and wasthen feddaily with 200 grammes of meat, 100 grammes of lime, 400 grammes of starch, and 500 grammes of sugar, made into a preparationvery acceptable to the dog. The gluten was occasionally added to the aliment to restrict the decomposition of the albumen. The experiment might be continued for twenty-five days; in the two last days diarrhoea set in, and the dog was killed in order todetermine precisely the contents of fat in the body. The weight of the body of the dog during the process of feeding had increased by four kilogrammes, and amounted at the end of the experiment to 27 kilogrammes. Of the albumen partaken only 800 grammes were left undccomposed in the whole body. At the outset, therefore, it could be inferred that the dog had formed and deposited a considerable quantity of fat-an inference which was confirmed by the examination of the body. The fat of the underskin tissue and of the mesentery was carefully cut out, melted, and weighed. Then the amount of fat on the muscles was determined in particular samples, and the fat on all the muscles of the animal calculated. The fat of the liver was directly ascertained, and, finally, an account was taken of the fat of the bones, the nerves, and the other organs, which was admitted to be only half the amount which other physiologists had obtained on the same parts in an individual whose skin, muscle, and liver fat corresponded with that of the dog examined in the present case. Certainly the quantity of fat thus found was considerably less than the quantity actually formed during the time of the experiment. From this sum of fat deposited by the dog there was now deducted the total amount of the alimentary fat which had been appropriated, and of the fat which might have been formed from the decomposed albumen (12 percent.). The result was a remainder of over 900 grammes of fat formed by the dog, which was derivable neither from the alimentary fat nor from the decomposed albumen, and which had, therefore, to be attributed to the carbo-hydrates that had been copiously administered. The speaker instituted a second calculation, taking account of the assumption which had hitherto, however, never been proved or even rendered probable by a single experiment, but was purely a deduction from constitutional formulae-the assumption, namely, that of the decomposed albumen as much as 51 per cent, might be utilised towards the formation of fat. But even under this supposition there still remained more than 400 grammes of fat formed by the dog which, contrary to the doctrine of Prof. Voit, must have been produced from the carbohydrates. In compliance with a suggestion thrown out in the discussion of the question the speaker had, furthermore, calculatedasa fat-formerthe wholeof the lime taken bythe dog, although all experiments had demonstratedthat lime in no case produced fat; and yet, after that item had beenfully takenaccount of, there were about 60 grammes of fat left that could be derived only from the carbohydrates. Dr. Munk therefore deemed it indisputably demonstrated by this experiment that in thecase ofcarnivorous as well as omnivorous and herbivorous animals carbohydrates might incertain circumstances contribute towards the formation of fat.—Dr. Hb'ltzke, following up a communication recently made by him respecting the influence of narcotics on pressure in the eye, reported experiments he had made con- ! cerning the influence of the blood-pressure on the intra-ocular pressure. The view had hitherto been universally accepted that the pressure in the eye was dependent on the blood pressure, and a series of experiences and experiments had been collected by way of proving this dependence. The nerves had likewise shown that they exerted an influence on the pressure in the eye, so far as they influenced the vascular system. Of the sympathetic in particular it was asserted that its paralysis induced an aug mentation, whereas stimulation of the nerve caused a diminution of the intraocular pressure, and this converse process was said to be connected with the expansion and contraction of the vessels. Seeing, however, that some investigators maintained that the effect of the sympathetic on the pressure of the eye was exactly the opposite to that just referred to, the speaker had institutednew measurements by means of a manomete r, utilising t^e second eye in the way of control. The result at wfc:ch he arrived by this means was that the cutting of the sympathetc always entailed an abatement of the pressure to an average of 6 mm. mercury, and that stimulation of the peripheral nerveending caused an increase of the pressure amounting to 14 mm. mercury. Stimulation of the supreme ganglion of the sympathetic had the same effect. If the veins of the neck were bound on the under side and the carotid was compressed then had neither the cutting nor the stimulation of the sympathetic absolutely any effect on the pressure in the eye-a proof that theinfluence of the sympathetic as above stated was only mediate, that the paralysis of the sympathetic induced the lowering of th eocular pressure only in consequence of the decrease of pres surein the vascular system and that the stimulation of the nerve caused the increase of the intra-ocular pressure only because of a rise of pressure in the blood. An experiment with a view to measuring the influence of the sympathetic on an atropinised eye did not yield perfectly decisive results, a circumstance which determined the speaker to investigate once more the influence of atropine on the ocular pressure. The result was somewhatdifferent from that recently communicated. It was now ascertained with perfect certainty that the influence of atropine by itself was a diminution of the ocular pressure and therefore the contrary of that of eserine. Only when the pupil was power fully expanded by the atropine did the pressure in the eye rise in correspondence with the other experiences that each expansion of the pupil was accompanied by an augmentation of pressure, and each contraction of the pupil was followed by an abatement of the ocular pressure. On the expansion and contraction of the pupil, the rise or the reduction of the blood-pressue became,in turn observable, and this latter again on its side generated arise, or, as it might be, a fall of the pressure in the eye. Thisparallelism of the ocular and the blood-pressure the speaker hadfound to hold good in all his experiments. The pressure in thevitreous body invariably showed the same changes as did thepressure in the watery chamber.
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Societies and Academies . Nature 32, 335–336 (1885). https://doi.org/10.1038/032335c0
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DOI: https://doi.org/10.1038/032335c0