PHYSIOLOGY OF THE INVERTEBRATA. 15 



Dr. Guckelberger (^Liebig's Annalen, vol. 64, p. 39) obtained 

 caproic, valeric, butyric, propionic, acetic, and formic acids by- 

 oxidising albumin with, potassium bichromate and sulphuric 

 acid. As these organic acids can be obtained artificially from 

 cyan-alcohols, it has been stated that albumin or protoplasm 

 is a compound of cyan-alcohols or cyanhydrins united to a 

 benzene nucleus. 



By looking upon albumin as built up of cyan-alcohols, we 

 can readily account for the formation of such compounds as 

 glycocine, leucin, the acids of the 0„H„n^,COOH series, as well 

 as those of the lactic series — occurring in the animal body. 



In the year 1828 Wohler converted ammonium cyanate 

 into urea; and Dr. Pfluger (Pjtiiger's ArcMv, vol. 10, p. 337), 

 in calling attention to the great molecular energy of the 

 cyanogen compounds, suggested that the functional meta- 

 bolism of protoplasm by which energy is set free, may be 

 compared to the conversion of the energetic unstable cyanogen 

 compounds into the less energetic and more stable amides. 

 In other words, that " ammonium cyanate is a type of living, 

 and urea of dead nitrogen, and the conversion of the former 

 into the latter is an image of the essential change which takes 

 place when a living proteid dies."* 



Dr. P. W. Latham, in " The Croonian Lectures" for 1886, 

 ably argues from experimental data that albumin or proto- 

 plasm has the following constitutional formula : 



* See Foster's Text-booh of PJiysiology (4th ed.), p. 749. 



