TRANSACTIONS OF SECTION B. 513 



regard to proteine, he says: — 'AH the organic nitrogenised constituents of the 

 body, how different soever they may be in composition, are derived from proteine. 

 They are formed from it by the addition or subtraction of the elements of water 

 or of oxygen, and by resolution into two or more compounds.' 



He seeks to trace the changes occurring in the conversion of the constituents of 

 Ibod into blood, of those of blood into the various tissues, and of these into the 

 secretions and excretions. 



He states that the process of chymifieation takes place in virtue of a purely 

 ■chemical action, exactly similar to those processes of decomposition or transforma- 

 tion which are known as putrefaction, fermentation, or deca}'. Thus, the clear 

 gastric j uice contains a substance in a state of transformation, by the contact of 

 which with the insoluble constituents of the food they are rendered soluble, no 

 other element taking any share in the action excepting oxygen and the elements of 

 water. All substances which can arrest the phenomena of fermentation and putre- 

 faction in liquids, also arrest digestion when taken into the stomach. Putrefying 

 blood, white of egg, flesh, and cheese produce the same effects in a solution of 

 .<ugar as yeast or ferment ; the explanation being, that ferment, or yeast, is nothing 

 but vegetable fibrine, albumen, or caseine, in a state of decomposition. 



Referring to the derivation of the animal tissues, he says they all contain, for a 

 • liiven amount of carbon, more oxygen than the nitrogenous constituents of blood. 

 In hair and gelatinous membrane there is also an excess of nitrogen and hydrogen, 

 and in the proportions to form ammonia. We may suppose an addition of these 

 ■elements, or a subtraction of carbon, the amount of nitrogen remaining the same. 

 The gelatinous substance is not a compound of proteine ; it contains no sulphur, no 

 phosphorus ; and it contains more nitrogen, or less carbon, than proteine. 



He next, as he says, attempts to develop analytically the principal metamor- 

 phoses which occur in the animal body. He adds that the results have surprised 

 himself no less than they will others, and have excited in his own mind the same 

 doubts as others will conceive. He nevertheless gives them, because he is con- 

 vinced that the method by which they have been obtained is the only one by which 

 we can hope to acquire an insight into the nature of organic processes. 



Referring to the animal secretions, he argues that they must contain the pro- 

 ducts of the metamorphosis of the tissues. He says a starving man with severe 

 exertion secretes more urea than the most highly fed individual in a state of rest ; 

 and he combats the idea that the nitrogen of the food can pass into urea without 

 having previously become part of an organised tissue. 



Having shown the chemical relations of bile and urine to the proteine bodies, 

 he illustrates, by formulae, the connection between allantoiue and the constituents 

 of the urine of animals that respire. He insists that in the herbivora the carbo- 

 hydrates must take part in the formation of bile ; and he calculates the number 

 of equivalents of proteine, starch, oxygen, and water, which would yield a given 

 number of equivalents of urea, choleic acid, ammonia, and carbonic acid. The non- 

 nitrogenous constituents in the food of the herbivora retard the metamorphosis of 

 the nitrogenous bodies, rendering this less rapid than in the carnivora. It may be 

 riaid that proteine, starch, and oxygen give the secretions and excretions — carbonic 

 acid by the lungs, urea and carbonate of ammonia by the kidneys, choleic acid by 

 the liver. It is the study of the phenomena which accompany the metamorphoses 

 of the food in the organism, the discovery of the share which the atmosphere and 

 the elements of water take in these changes, by which we shall learn the conditions 

 necessary for the production of a secretion or of an organised part. 



He traces the possible formation of taurine from caffeine or asparagine by 

 t]ieir_ assumption of oxygen and of the elements of water. And from the com- 

 position of the vegetable alkaloids he suggests the possibility of their taking a 

 share in the formation of new, or the transformation of existing, brain and nervous 

 matter. 



Finally, in reference to these various illustrations and considerations, he says, 

 however hypothetical they may appear, they deserve attention in so far as they 

 point out the way which chemistry must pursue if she would really be of service 

 to physiology and pathology. Chemistry, he savs, relates to the conversion of food 



1880. L L " 



