Chapter X — 113 — Duality of the Ghondriome 



tic forms : granules, rods and filaments, capable of changing from 

 one shape to the other. They offer, moreover, and this is much 

 more important, the same histophysical characteristics (same re- 

 fractivity, same viscosity, same process of alteration) and the 

 same histochemical characteristics, even to their behavior with a 

 great number of chemical reagents and dyes. For these reasons, 

 it is generally impossible to tell them apart in embryonic cells of 

 plants in which chlorophyll is not continuously elaborated. The 

 plastids, therefore, are distinguished from other chondriosomes 

 only by the fact that they are the centers of very active elabora- 

 tions which, considerably modify their shape. This is true in cells 

 lacking in chlorophyll in which plastids elaborate starch, and espe- 

 cially true in green cells in which the plastids become voluminous 

 because of the chlorophyll which they accumulate. Moreover, these 

 modifications of form may be only transitory. The amyloplasts in 

 cells without chlorophyll, as soon as the starch has been absorbed, 

 go back to their forms of typical chondriosomes. The chloroplasts 

 themselves may in some cases lose their chlorophyll and return 

 to their original state as chondriosomes. In a word, the chondrio- 

 somal form is the form taken by these organelles during the func- 

 tionally inactive period. The only distinction, therefore, that exists 

 between the animal and fungal cell on the one hand, and the cell 

 of the green plant on the other, is the presence of plastids, the 

 second category of chondriosomal elements. This distinction is re- 

 lated to the existence of the chlorophyll function which charac- 

 terizes green plants. 



These facts, now exactly demonstrated by our work and that 

 of our students, carried on over a period of thirty years, have led 

 us to fomiulate the theory of the duality of the chondriome in 

 chlorophyll-containing plants. This consists in stating that the 

 chondriosomes of chlorophyll-containing plants are composed of 

 two categories having between them the same relationships which 

 the heterochromosomes bear to the autochromosomes, the first cate- 

 gory (the genuine chondriosomes) being very similar to the chon- 

 driosomes of animals and fungi, the second category (the plastids) 

 composed of a supplementary line of chondriosomes related to 

 photosynthesis, which characterizes these plants. It is obvious 

 that the two categories must, after all, possess differences in chem- 

 ical constitution. Otherwise it could not be explained why one 

 has functions which the other does not have. Nevertheless these 

 differences, probably very slight, do not appear during histo- 

 chemical analysis. In any case, both categories of elements have 

 very closely allied lipoprotein constitutions and form in the cyto- 

 plasm a disperse lipoprotein phase. They are differentiated only 

 by one of them manifesting a function which is lacking in the 

 other. 



The question is therefore definitely solved as far as the facts 

 are concerned and it is demonstrated that the chondriosomes and 

 plastids are two individual cellular components with the same 

 lipoprotein constitution, capable of presenting identical shapes but 



