Guilliermond - Atkinson 



— 98 



Cytoplasm 



Figure 60 gives a very exact idea of these facts. Here, in the 

 pumpkin seedling, are shown side by side all the forms assumed 

 by the two categories of elements in the course of cellular differ- 

 entiation. It is seen that the two types of chondriosomes have 

 the same shape through all the stages of cellular development — 

 granules, rods, filaments — but these shapes are not always identical 

 for both types at a given stage in development and there are stages 

 in which one type appears as granules and the other as filaments. 

 This makes it possible to distinguish them at every stage. Further- 



,— >i 



T-C 



J.^^..^ 



Fig. 66. — A-D, Epidermal cells of petal of tulip, c, leucoplasts; vi, chondrio- 

 somes; gg, lipide granules. B, beginning of change in leucoplasts. C, vesicula- 

 tion. D, cells fixed by Regaud's method. E-H, filament of Saprolegnia. n, nu- 

 cleus; c, chondriocont. F, beginning of change in chondriosomes. G, vesiculation, 

 V, vesicle. H, filament fixed by Regaud's method. 



more, the two categories of elements are capable of division and 

 frequent stages in division are observed. 



If these two categories of elements are compared with the 

 chondrioconts in liver cells of the frog or with those in fungi, as 

 represented in Figures 60 and 61 {cf. also pp. 85 and 113), it is seen 

 in a general way that it is the plastids which most resemble the 

 animal chondriosomes and those of the fungi. 



In a general way also, the inactive chondriosomes are a little 

 smaller than animal chondriosomes and are less frequently found 

 as chondrioconts. The plastids in general have the same dimen- 

 sions as the chondriosomes of animal cells but in certain phases 

 become much more voluminous. 



