THE CELL AND PROTOPLASM. 93 



Chemical study of the same substance was of 

 no less interest than the microscopical study. 

 Of course it was no easy matter to collect this 

 protoplasm in sufficient quantity and pure enough 

 to make a careful analysis. The difficulties were 

 in time, however, overcome, and chemical study 

 showed protoplasm to be a proteid, related to 

 other proteids like albumen, but one which was 

 more complex than any other known. It was 

 for a long time looked upon by many as a single 

 definite chemical compound, and attempts were 

 made to determine its chemical formula. Such 

 an analysis indicated a molecule made up of 

 several hundred atoms. Chemists did not, how- 

 ever, look with much confidence upon these 

 results, and it is not surprising that there was 

 no very close agreement among them as to the 

 number of atoms in this supposed complex 

 molecule. Moreover, from the very first, some 

 biologists thought protoplasm to be not one, 

 but more likely a mixture of several substances. 

 But although it was more complex than any 

 other substance studied, its general characters 

 were so like those of albumen that it was uni- 

 formly regarded as a proteid ; but one which was 

 of a higher complexity than others, forming per- 

 haps the highest number of a series of complex 

 chemical compounds, of which ordinary proteids, 

 such as albumen, formed lower members. Thus, 

 within a few years following the discovery of pro- 

 toplasm there had developed a theory that living 

 phenomena are due to the activities of a definite 

 though complex chemical compound, composed 

 chiefly of the elements carbon, oxygen, hydrogen, 



