Morphological Units 43 



light important conclusions concerning many compounds 

 developed from protoplasm. But whether those com- 

 pounds were present, as such, in the living protoplasm, or 

 have only developed after death, or through the influence 

 of reagents, as products of decomposition, is another 

 question. 



The chief point for the theory of heredity is, however, 

 that protoplasm always offers us certain historical char- 

 acters besides physical and chemical properties. It is to 

 these that it owes its peculiarity. A synthetic composition 

 of protein bodies is no longer regarded by anybody as an 

 impossibility; but whether we shall ever succeed in ob- 

 taining living protoplasm in any other than the phyloge- 

 netic way, will probably remain for a long time a matter of 

 well-founded doubt. 



The historical characters demand a molecular struc- 

 ture of such complicated nature that the chemistry of the 

 present time fails us entirely in our attempts at an ex- 

 planation. For the present, therefore, theory must be 

 content to accept the idea that protoplasm is composed of 

 morphological units. These, of course, must themselves 

 be built up from chemical molecules, and among the latter 

 the protein bodies must play an important role. To con- 

 clude from this fact, however, that protoplasm itself is a 

 protein body, seems not at all justified. 



Those invisible morphological units are of a hypothet- 

 ical nature and we will not follow up this subject any 

 further in this connection. I onlv wished to show how 

 this consideration also, leads us to that assumption of 

 pangens, with which we shall have to deal in the last two 

 chapters of this section. 



