1915] 



CZAPEK — PROTOPLASM AND ITS COLLOIDAL PROPERTIES 243 



trituration of the cells, if precaution is taken to prevent 

 change in the material by bacterial action. But the essential 

 difference between such autodigestion and the life-process 

 consists in the fact that the first is not ruled by the laws of 

 correlation and regulation, which are so peculiar to life pro- 

 cesses. Nevertheless, we cannot say that the whole of the 

 life-mechanism is destroyed by grinding down living organs. 

 At least a part of it cannot immediately be transformed by 

 this type of disintegration. From this we may draw the con- 

 clusion that there are certain chemical substances present in 

 protoplasm which are responsible for certain activities of 

 the living tissue. Such substances are the enzymes, which 

 are entirely unknown in inanimate nature, and absolutely dis- 

 tinctive of cell protoplasm. Further, we cannot suppress some 

 scruple that in Reinke's analysis there were examined not 

 the original protein-bodies of protoplasm, but only substances 

 artificially produced during the treatment of the original 

 material. 



Our chief objection against the "Engine-Theory" of proto- 

 plasm is that no mechanism has hitherto been known which 

 may be destroyed by heat as easily as is protoplasm, whilst 

 on the other hand one cannot immediately and entirely destroy 



it merely by pounding to an impalpable pulp. Besides this, 

 recent investigations on the proteids of animal organs — in 



which great care was taken to dry the pulp quickly at a tem- 

 perature as low as possible — have shown that there really 

 exist highly compounded protein bodies of hitherto unknown 

 constitution which have to be considered as real constituents 

 of protoplasm. 



Can such discoveries in some way explain the vital prop- 

 erties of the cell? It seems as if we may not understand the 

 wonderfully accurate working-together of all organs in cells 

 without supposing trans-microscopical structural qualities; 

 but we need not assume any mysterious new forces or struc- 

 tures. Most of the well-known characteristics of protoplasm 

 can be understood by considering further the colloidal state of 

 the constituents of the cells. 



