THE PROTEIN MOLECULE 93 



acid was possible for cyanogen may react with 

 boiling hydroiodic acid with the development of 

 amino acetic acid and from this the other amino 

 acids found in the protein molecule might have 

 been developed. In this view, proteins in their 

 simplest form may have come into existence 

 long before life as we now know it was pos- 

 sible on the earth. 



The simplest protein, as the protein poison, 

 has its intense chemism satisfied as it combines 

 with other elemental groups in the development 

 of the more complex bodies. 



I began my work with the hope of finding 

 simple proteins in the cellular structures of 

 bacteria. In this I was disappointed and I now 

 see that I should not have expected it. Instead 

 of finding simple proteins in bacterial cells I 

 have found them in the casein of milk and in 

 the proteoses of seeds. As I have already said 

 the young mammalian is fed upon food prin- 

 ciples served in the simplest form. The nurs- 

 ing child is supplied with fats as such, with 

 mineral constituents for the most part uncom- 

 bined, with carbohydrates in the easily assimi- 

 lable form of lactose and with amino acids in the 

 relatively simple protein, casein. The sprouting 

 seed finds the amino acids with which it starts 

 life in the relatively simple proteins while fats 



