Chapter XI 



HYPOTHESES RELATIVE TO THE ROLE OF 

 CHONDRIOSOMES AND PLASTIDS 



It has just been seen that cytological investigations, carried 

 out during recent years, have shown that the cytoplasm always 

 contains in suspension various inclusions, among which the most 

 important are the chondriosomes to which, in chlorophyll- 

 containing plants, are added the plastids. The latter present a close 

 analogy to the chondriosomes but may be considered as a line dis- 

 tinct from these elements. 



Immediately, this raised the question as to the role of the 

 chondriosomes and plastids. We find ourselves here on uncertain 

 ground, for it must be recognized that if, at the present moment, 

 our morphological knowledge is very advanced, we are still ex- 

 tremely ill-informed as to the role which must be attributed to 

 these various elements in the functioning of the cell. As Devaux 

 says, "The fact is that we do not sufficiently know the inner organ- 

 ization of the cell, for all that a microscopic study makes possible 

 is a first approximation, manifestly incomplete. We should, for 

 complete knowledge of the cellular mechanism, be able to reach 

 the molecules themselves, that is, the elementary particles of the 

 cell, and study them from the triple point of view of structure, of 

 molecular attractions and movements, as well as from the point 

 of view of reciprocal relations." Perhaps some day the progress 

 of physical chemistry will give us precise information on this 

 point, but for the moment we must be content with hypotheses 

 which are still very vague and which we will take up here as 

 briefly as possible. Investigations at the beginning of the study 

 of chondriosomes led various authors, Regaud in particular, to 

 attribute to the chondriosomes of animal cells, an important role 

 in the phenomena of secretion. According to this opinion the 

 chondriosomes are organelles through whose agency are elaborated 

 very diverse products of cellular activity: zymogen granules, fats, 

 pigments, i.e., the chondriosomes have a role exactly like that of 

 the plastids in chlorophyll-containing plants. Thus the chondriome 

 appears as the secretion apparatus of the cell. Although the in- 

 vestigations in plant cytology have demonstrated the very curious 

 fact that it is precisely the plastids of chlorophyll-containing plants 

 which show exactly the same forms and the same histochemical re- 

 actions as the chondriosomes, we have seen, however, that more 

 accurate research on animal cells and on the thallus of fungi, 

 employing the control methods of direct observation of living ma- 

 terial and of vital staining, have not been able to confirm this 

 secretory role except in exceptional cases (Noel). The direct par- 

 ticipation of chondriosomes in phenomena of secretion seems to us 

 therefore to be hypothetical and in reality we know nothing as to 



