214 



LECTURE X. 



ceptible to direct proof; because, in the first place, we are not acquainted 

 with all the albumin cleavage-products, and, on the other hand, many of 

 the amino acids are evidently destroyed during the complete hydrolysis by 

 acids and alkalies. 



Closely related to this question, is the problem whether the organism is 

 capable of getting along with albuminous substances which are deficient 

 in specific groups. Under normal conditions we constantly consume a 

 mixture of proteins. Based on the above conception, regarding the degra- 

 dation and reconstruction of the albumins, we can imagine that it is imma- 

 terial whether one or the other protein, or this or that elementary 

 constituent, is absent. The fact that they are all finally present in the 

 digesting mixture is the important consideration. We can also imagine 

 that the animal organism possesses the ability of producing certain amino 

 acids from others; for instance, glycocoll. That an organism can get 

 along with an albuminous substance in which glycocoll is entirely absent, 

 is evident from the feeding experiment mentioned, in which the cleavage- 

 products of casein were used. 



