49 CYTOMORPHOSIS 



each single organ there comes about, so to speak, an exaggera- 

 tion of a single function. Protoplasm is sensitive and 

 irritable. In our case, our sense organs take care of the 

 sensations to the advantage of the whole body. Protoplasm 

 has contractility, and this function is assumed by the muscles 

 again to the advantage of the whole body. Similarly, the 

 glands take over the formation of secretions — the excretory 

 organs, the elimination of urea, etc. Now we know that the 

 various structures which we can see in protoplasm, and which 

 are characteristic for the sense organs, muscles, gland cells, 

 etc., determine in each case the special performances of their 

 respective cells. Briefly expressed, the whole meaning of 

 differentiation is physiological. The peculiarities which we 

 can recognize with the microscope in differentiated cells exist 

 in order to render it possible for the cells to accomplish 

 their special activity. It would be superfluous to Hnger over 

 this conception, to ampUfy, or even to justify it by a rounda- 

 bout demonstration. I wish, however, to specially emphasize 

 the fact that the entire doctrine of cytomorphosis renders 

 it clear that structure inUving substance is the essential 

 thing. This has become clear to us from the phenomenon of 

 differentiation. We may probably go stiU further and say 

 that even in those cases in which we as yet cannot recognize 

 any microscopic structure, structure is still present. The 

 conception of the significance of structure — of organization, 

 which we win from the investigation of differentiated cells, 

 applies also to protoplasm. It is well known, as I have 

 already mentioned, that protoplasm is chemically extremely 

 complicated, but the chemical combinations are not simply 

 mixed together as in a simple solution, but are in part sepa- 

 rated spatially. When we state that the living substance 

 has organization we base our view not only on the application 



