THE PROTEINS, THEIR CONSTITUTION 221 



the simplest so far obtained — namely, the protones — bodies 

 allied to the peptones, whose molecules are much simpler. Thus 

 Sturin, obtained from the sturgeon, is 



C H N 



36 69 19 7 



Only yesterday my colleague Professor Ruttan showed me a fat 

 formed from the hydrocarbon C H which he had built up in 

 the laboratory ; so here it will be seen that we are within the 

 limits of possible synthesis. Kossel showed that these can be 

 broken down into yet simpler bodies of the amino-acid group, 

 Histidin, Arginin, and Lysin, C 6 H 9 N 3 2 , etc. In fact, the re- 

 searches of Curtius, Hofmeister, and Emil Fischer have demon- 

 strated that the proteins in general are composed of these 

 amino-acids — that they are compound molecules composed of 

 these amino-acids joined in series. I do not wish to enter too 

 deeply into so complicated a subject. I will only say that 

 the amino-acids are compounds of carbon, hydrogen, nitrogen, 

 and oxygen that have the structure of fatty acids — bodies 

 of the butyric and acetic acid group — to which nitrogen- 

 containing amine molecules (of NH 2 ) have become linked, giving 

 them the remarkable property of being at the same time basic 

 as well as acid, so that they can enter into combination at one 

 and the same time with acids and bases. It is this particular 

 property that would seem to be at the bottom of their striking 

 characteristic of forming huge compound molecules. Thus, 

 suppose we regard them as bricks, having at one end an acid 

 affinity which will attract and attach a basic body, and at the 

 other a basic affinity which will attract and combine with an 

 acid body (or perhaps better as a succession of magnets, attracted 

 the positive pole of one to the negative pole of the other), it will 

 be seen how thereby it is possible to build compound molecules 

 formed of long chains of these amino-acids. And proteins are 

 bodies of this nature. 



This is no longer a matter of theory. The long-continued 

 studies of the great German chemist Emil Fischer have in the 

 last few years been crowned with brilliant success. Briefly, he 

 has not only isolated a long series of these amino-acids, but, 

 following Curtius, has been able to synthesize them, that is, to 

 make them in the laboratory from simpler substances ; but also, 



