ORGANIC PROCESSES OF PLANTS AND ANIMALS. 1019 



casein, the last existing in milk and being the basis of cheese. 

 Two very important conclusions have lately been drawn re- 

 specting the relations of these substances to each other, and 

 their origin in the vegetable kingdom. The first is a deduction 

 from the analysis of these substances by M. Mulder, which 

 has been repeated and confirmed in the Giessen laboratory, 

 namely, that these three substances are identical in composition. 

 The following are the results of M. Mulder's analyses : 



FIBRIN. ALBUMEN. CASEIN. 



Of eggs. Of serum. 



Carbon . . 54.56 54.48 54.84 54.96 



Nitrogen . . 15.72 15.70 15.83 15.80 



Hydrogen . 6.90 7.01 ?.09 J.15 

 Oxygen "] 



Phosphorus > 22.82 22.81 22.24 22.09 

 Sulphur J 



100. 100. 100. 100. 



The proportion of the carbon to the nitrogen in these sub- 

 stances is that of 8 equivalents of the former to 1 of the latter. 

 They differ slightly in the minute quantity of phosphorus and 

 sulphur with which they are accompanied. They all dissolve 

 in concentrated hydrochloric acid, with the aid of heat, and the 

 solutions kept for a time at a pretty high temperature, first 

 assume a beautiful lilac, and then a rich violet blue colour. 

 At this stage of the decomposition, each of the three substances 

 re-acts in the same way with carbonate of ammonia and other 

 re-agents. With considerably different physical properties, 

 they appear to be modifications of a common principle, which 

 Mulder names Protein, and expresses by C 40 H 31 N 5 O 12 ; Liebig, 

 by C 48 H 36 N 6 14 . 



The second conclusion is the observation of M. Liebig, that 

 animals draw these principles ready formed from the vegetable 

 kingdom, and do not organise them. The parallel vegetable 

 principles are vegetable fibrin, a constituent of gluten first pro- 

 perly distinguished by Liebig, and gluten itself, vegetable albu- 

 men, and legumin, or as it is termed by Liebig, vegetable 



