Chapter X 



105 



Duality o£ the Ghondriome 



All these facts lead us to the conclusion that the two categories 

 of cytoplasmic organelles in chlorophyll-containing plants both 

 show the characteristics of chondriosomes and it is evident that 

 there is no criterion, unless it is the ability of the plastids to form 

 starch and chlorophyll, for including the inactive chondriosomes 

 rather than the plastids in the formations known in animal cells as 

 chondriosomes. On the contrary, the plastids by their elongated 

 chondriocontal forms sometimes resemble the chondriosomes of 

 animals even more than do the inactive chondriosomes of plants. 



Fig. 74. — Fern sporangia. Successive stages in the return to a homo- 

 seneous chondriome by resorption of starch and loss of pigment in the chloro- 

 plasts. 1-3, Asplenium Ruta-muraria. 1, sporogenous cells; 2, spore mother 

 cells; 3, tapetum and spore mother cells. 4, Pteridium; tetrad and tapetum. 

 Regaud's method. (After Emberger). 



The plastids are sometimes, however, slightly larger. Further- 

 more, the inactive chondriosomes unquestionably have the charac- 

 teristics of chondriosomes from which it is impossible to separate 

 them, as Meves does, for they, too, show in a great number of cases 

 the form of typical chondrioconts. 



These two categories of elements, therefore, fit the definition 

 of chondriosomes. They correspond to organelles seeming to be 

 incapable of forming other than by division, they have the shape 



