230 ORIGIN OF STRUCTURES AND FUNCTIONS 



nature proceeded, so the idea became stronger and stronger 

 in the minds of scientists that albumens are present in all 

 organisms and that these compounds play an extremely 

 important part in the process o£ life. This idea received 

 precise expression in the name given to albumens in the 

 1830s by G. J. Mulder.^ He called them protein, from the 

 Greek word Trpiarelos (first or most important). In using this 

 term Mulder was thus stressing the biological aspect of protein 

 as the most important component of living material. At that 

 time chemical knowledge of proteins was very meagre. Pro- 

 teins attracted the attention mainly of biologists, who usually 

 regarded them as the main and most important components 

 of the gelatinous material within the cell. This material was 

 called ' protoplasm ' by H. v. MohP in the middle of the 

 nineteenth century and the part it plays as the material 

 carrier of life became more and more evident. Some bio- 

 logists of the latter half of the nineteenth century even 

 identified protoplasm with protein and among them E. 

 Haeckel,* for example, considered that the simplest organisms 

 consisted of nothing but lumps of proteinaceous substances. 



F. Engels,^ in common with the biologists of his time, often 

 used the terms ' protoplasm ' and ' albuminous bodies ' 

 (Eiweisskorper). The ' proteins ' of Engels must therefore 

 not be identified with the chemically distinct substances 

 which we have now gradually succeeded in isolating from 

 living things, nor with purified protein preparations com- 

 posed of mixtures of pure proteins. Nevertheless Engels^ was 

 considerably in advance of the ideas of his time when, in 

 speaking of proteins, he specially stressed the chemical aspect 

 of the matter and emphasised the significance of proteins in 

 metabolism, that form of the motion of matter which is 

 characteristic of life.* 



It is only now that we have begun to be able to appreciate 

 the value of the remarkable scientific perspicacity of Engels. 

 The advances in protein chemistry now going on have 

 enabled us to characterise proteins as individual chemical 



* Carl Schorlemmer expressed very similar ideas (The rise and development 

 of organic chemistry, pp. 122-3. Manchester and London, 1879). This 

 topic must have been discussed by Engels and Schorlemmer during their 

 years of friendship in Manchester. — Translator. 



