l8o FINE-STRUCTURE OF PROTOPLASM II 



either substantially by chemical compounds (e.g., hydration) or only 

 in its configuration in space (e.g., by changes in the distance between 

 decisive groups) in such a way that they can no longer fulfil their 

 task. These morphogenetic groups often require hormones to be 

 activated (Hadorn, 1939). 



Since the morphogenetic faculties are assigned to special cells, 

 whereas certain metabolic phenomena, such as respiration, are com- 

 mon to all cytoplasts, a morphological separation of these manifes- 

 tations of life in the submicroscopic domain is probable. 



As previously pointed out, the submicroscopic microsomes must 

 contain a considerable number of protein macromolecules and other 

 compounds such as nucleic acids, phosphatides, lipids, pigments, etc. 

 These constituents must be united in some very specific pattern. This 

 follows from the fact that their arrangement is capable of specific 

 achievements in biosynthesis. Just as in organic chemistry an asym- 

 metric synthesis is only possible if another optically active compound 

 with asymmetric carbon atoms is present which prevents the form- 

 ation of racemic mixtures, so, too, the organization of biocatalysts 

 must be adequate to the chemical structure of the specific compounds 

 synthesized. For here, as in the case of asymmetric synthesis, the 

 theorem applies: Specific structures can he formed only hj the agency of 

 corresponding structures. 



The chemical compounds of the cytoplasm would not be capable 

 of accomplishing any useful work without definite positions in space. 

 The prosthetic group (coenzyme) of an enzyme is only active when 

 attached to a special protein carrier (apoenzyme). Although the 

 chemical forces of their linkage are not considerable, and the coenzyme 

 can therefore be split off and recombined with the macromolecular 

 carrier with comparative ease, the system is only effective when the 

 prosthetic group takes up its specific steric position. 



When the enzymes are located in individual particles such as micro- 

 somes or mitochondria, they can be separated from the other cell 

 constituents and examined in the isolated state. In the case of the 

 endoenzymes, however, which cannot be extracted from the tissues 

 (Bersin, 1939), the apoenzyme may be a part of the cytoplasmic 

 framework, in which case there is, of course, no possibility of dis- 

 tinguishing metabolic from structural cytoplasmic constituents. 



In connection with the foregoing it is necessary to stress the fact 



