PHYSIOLOGY OF THE INVERTEBRATA. 17 



This substance, whose composition is CyjHijgNjgO^sS, differs 

 from Dr. Lieberkuhn's empirical formula (C^aHj^^NjgOjjS) only 

 by six atoms of hydrogen. 



According to Latham, albumin " is a compound of cyan- 

 alcohols united to a benzene nucleus, these being derived 

 from the various aldehydes, glycols, and ketones, or that they 

 may be formed in the living body by the dehydration of the 

 amido-acids ; that from a body so constituted all the different 

 substances may be obtained which have been extracted from 

 albuminoid tissues ; that lactic acid is obtained in two ways, 



either from OjH^t^^p^ or from changes and condensation in 



0H2\p„ with the simultaneous development of carbonic 



anhydride, a result which is brought about when a muscle 

 contracts or when it dies; and that urea may be obtained 

 from one series of cyan-alcohols with the production of a 

 cyan-alcohol higher in the series. 



" Such a compound of cyan-alcohols therefore, presenting 

 so much resemblance in its properties to albumin, cannot 

 differ very widely (though perhaps not absolutely correct) 

 from the molecular constitution of albumin. 



" Taking this view, then, of the constitution of albumin, the 

 following may be given as a summary of the nutritive 

 changes : The amido-acids — glycocine, leucin, tyrosin, &c. — in 

 passing from the alimentary canal to the liver, are dehydrated, 

 forming a series of cyan-hydrins or cyan-alcohols attached to 

 a benzene nucleus, and then pass into the circulation. In the 

 tissues these cyan-alcohols, partly by condensation, partly by 

 hydration and oxidation, give rise to the various effete 

 products which are eliminated from the system in the form 

 of carbonic acid and urea." 



There is no doubt that the theory of protoplasm being 

 a complex molecule,* derived from various aldehydes, glycols, 



* See also a paper by Dr. P. Schiitzen in the ComptesSendus, tome 112, 

 p. 198. 



B 



