PHYSIOLOGY. 



665 



toxic properties. Experiments are cited that 

 show the extent to which the frog's liver can 

 retain and digest such poisons as hyoscyamine 

 and utilize the products derived from them as a 

 food supply for the organs. 



Nutrition. The nutritive value of gelatin 

 has been studied by Dr. J. Munk in experiments 

 on a dog. Till the present time it was only 

 known that gelatin alone could not make good 

 the need for proteids, but that a diet of gelatin 

 with some proteid leads to a reduction of proteid 

 metabolized. The author had propounded the 

 question, How far can gelatin take the place of 

 proteids ? and had carried on an experiment of 

 four days' duration. After the dog had been 

 placed in nitrogenous equilibrium on a diet of 

 meat-meal, rice, and fat containing 9 2 grains of 

 nitrogen in the form of proteid, five sixths of this 

 nitrogen was replaced by nitrogen in the form of 

 gelatin. The animal continued in nitrogenous 

 equilibrium. It appears from this that by the 

 administration of gelatin the nitrogen necessary 

 as proteids can be reduced far below the mini- 

 mum metabolized in starvation without any be- 

 ginning metabolism of tissue nitrogen. 



The result of the long-continued investiga- 

 tions of Dr. Pavy of the physiology of the car- 

 bohydrates and their fate in the animal body is 

 the conclusion that sugar in being absorbed from 

 the alimentary canal combines with some pep- 

 tone to form a proteid, and that the proteid gen- 

 erally has a glucoside'constitution. After their 

 entrance into the circulation the proteids may 

 again undergo decomposition or disintegration, 

 leading to the separation, as a clearage product, 

 of sugar or of fat, the former, if abundant, mak- 

 ing its appearance in the urine. 



By extraction with glycerin Claude Bernard 

 obtained from liver a ferment which converted 

 glycogen into sugar, but the properties of the 

 sugar were not described. In a research by Miss 

 M. C. Tebb it was found that pig's liver, rapidly 

 dried, produced dextrose when allowed to act on 

 starch or glycogen. In all cases, whether an ex- 

 tract or the dried tissue was used, the product of 

 the action on starch or glucose gave crystals of 

 phenyl glucosazene with phenyl hydrazin, and 

 the reducing power increased only slightly on 

 boiling with acid ; hence the conclusion was 

 drawn that one product of the action is dextrose. 

 As far as they have gone experiments with fresh 

 liver have given the same result. 



In a renewed examination of Heidenhain's ex- 

 periments dealing with the action of peptone on 

 lymph formation^E. H. Starling found that the re- 

 sults did not justify that author's conclusion that 

 lymph should be regarded as a secretion, while 

 they might be explained if lymph production were 

 looked upon as dependent on the two factors of 

 intracapillary pressure and permeability of the 

 vessel wall. A fresh investigation was there- 

 fore made, from which Dr. Starling draws con- 

 clusions confirming the view expressed above ; 

 and, further, that members of Heidenhain's sec- 

 ond class of lyrnphagogues including crystal- 

 loids, such as sugar, salt, etc. on injection into 

 the blood attract water from the tissues and 

 cause a condition of hydroemic plethora with in- 

 creased capillary pressure, the increased lymph 

 flow from the thoracic duct being due to the in- 

 creased pressure in the abdominal cavities,- and 



that members of Heidenhain's first class of lym- 

 phagogues including such substances as pep- 

 tone, leech extract, crawfish extract, etc. affect 

 injuriously the endothelial cells of the capillaries, 

 especially in the liver, increasing their perme- 

 ability ; the muscular walls of the blood vessels, 

 especially in the splanchnic area, producing vas- 

 cular dilatation ; and the heart muscle. The in- 

 creased flow of lymph is due to the increased 

 permeability of the hepatic capillaries, nearly the 

 whole of the increased lymph flow being derived 

 from the liver. 



Having discovered that the excretion of chlo- 

 rine, phosphorus, lime, and magnesia was in- 

 creased in man during hunger, Dr. J. Munk, in 

 some experiments on dogs, found that during 

 ten days of fasting all four of these substances, 

 especially phosphorus and lime, in largely in- 

 creased quantities in the urine, as compared with 

 days of normal dieting, and increased amounts of 

 phosphorus, lime, and magnesia in the faeces. By 

 calculating, from the amount of nitrogen ex- 

 creted, the amount of body proteid metabolized 

 during hunger, he found that only a portion of the 

 excreted phosphorus could have come from the 

 proteid ; the remainder must have resulted from 

 the metabolism of some constituent of the body 

 rich in phosphorus and lime. The ratio of these 

 to each other corresponded to a metabolism of 

 bone substance amounting to about 39 grammes 

 in ten days of hunger. The author further re- 

 ported on experiments on dogs, in which he at 

 one time administered a given amount of meat 

 all at once, and at another time the same amount 

 of meat distributed over three meals. In the lat- 

 ter case the excretion of nitrogen in the urine was 

 greater than in the former, indicating a less per- 

 fect utilization of the proteid. This result on 

 dogs is, however, not applicable to man, in whose 

 case the conditions are different, and in whom, as 

 shown by Ranke's older experiments, a given 

 amount of food is more completely utilized if 

 taken in separate portions than if "eaten all at 

 once. 



Prof. A. Kossel, in his further researches on 

 thytnin, a decomposition product derived from 

 nucleic acid extracted from the thymus, has ob- 

 tained a substance that gives all the reactions of 

 levulinic acid, and produces a salt with silver 

 that possesses exactly the crystalline form of the 

 silver salt of levulinic acid. As levulinic acid 

 originates from levulose, and is viewed by many 

 chemists as proof of the presence of levulose, so 

 from the above reaction the presence of a carbo- 

 hydrate in nucleic acid is to be deduced. The 

 origin of the nucleic acid is indifferent for this 

 reaction, since it is found with all nucleic acids 

 a very important fact in relation to the physi- 

 ology of metabolism. The attempt to discover 

 a carbohydrate in the atom complex of casein, 

 closely related to nucleic acid, led to the discov- 

 ery of a substance that gave all the reactions of 

 levulinic acid, with the exception of the levulinic 

 acid salts, so that a certain conclusion as to the 

 presence of a carbohydrate complex in casein can 

 not be drawn. 



In the experiments of Dr. van Noorden and 

 Prof. Zuntz on the action of quinine on the 

 metabolism of man, with a constant diet extend- 

 ing over a long period, and after nitrogenous 

 equilibrium was established, daily increasing 



