CHAP. I.] THE PROTEIDS. 21 



C 5 H 9 N0 4 , which is a homologue of the preceding ; secondly, amides 

 having aromatic nuclei, such as tyrosine ; thirdly, amides containing 

 sulphur, such as cystine : fourthly, acids and aldehydes corresponding 

 to the radicals of the amides before mentioned. The proteid sub- 

 stances behave as amides containing both radicals of the higher homo- 

 logues of lactic and tartaric acids and residues of aromatic acids. 

 Hence" it follows that when the proteids are oxidized there is simul- 

 taneous production of fatty acids, of aromatic compounds and doubt- 

 less also of bodies analogous to urea. 



" Though all the proteids when they are decomposed or oxidized 

 nearly always furnish the same products, they yet do not furnish 

 them in the same proportions. It must therefore follow that the 

 different radicals which they contain differ, not only in their arrange- 

 ments, but in their relative proportion, and in some cases even in 

 their nature 1 ." 



The views ^ is beyond the scope of this work to discuss 



of Schtitzen- hypotheses as to the constitution of bodies unless these 

 berger 2 . appear to possess a legitimate interest to the biologist 



or the physician. The speculations of Schiitzenberger can therefore 

 only be summarized in a few words. From the products obtained 

 by the action of caustic baryta upon the proteids (see pp. 19 and 20), 

 this author looks upon the proteids as complex ureids, i.e. as resulting 

 from combination in different proportions of urea with amido-acids, 

 some of which belong to the leucine series, others to the aspartic 

 series, whilst the more complex products of decomposition allied 

 to leguminic acid must be considered as resulting from complete 

 decomposition. Tyrosine represents the aromatic group, and is the 

 source of benzoic acid found amongst the products of the putrefactive 

 decomposition of proteids. When decomposed by means of caustic 

 baryta, he assumes that the molecule of albumin, which he represents 

 by the empirical formula C 72 H m N 18 O w S, yields, in addition to urea, 

 acetic acid, and some sulphur-containing body, a substance to which 

 he ascribes the formula C^ H 132 N 14 34 and which he admits may be 

 split up in various ways. Useful, nay indispensable as are such 

 hypotheses as suggesting lines of research to the actual chemical 

 worker, they possess no interest as yet to the biologist. 



. , 3 It is in the cells of the organism that the processes 



views^reTative take P lace whose results are the external activities 

 to the consti- which it manifests; it is within the cells that the 

 tution of tiie oxidation processes of the economy have their seat. 

 Proteids. There is nothing more striking than the wide con- 



trast which exists between the non-living proteid matter, say that of 



1 Gautier, Chimie appliquee a la Physiologic, a la PatJwlogie et a VHygiene, tome 

 premier, p. 251. 



2 Schiitzenberger, " Kecherches sur 1'Albumine et les maticres albummoides, 

 Bulletin de La Soc. Chimique, v. 23 and 24. ,, 



3 Pfliiger, " Ueber die physiologische Verbrennung in den lebendigen Orgamsmen, 

 Pfliiger's Arcliiv, Vol. x 1 ., p. 251. 



