Chapter XX 



— 219 — Summary and Conclusions 



much smaller chloroplast, provides an intermediate step between 

 algae which have only a single, permanent, very differentiated, 



Fig. 151. — Diagrammatic representation of the structure of 

 phanerogam cells during development, based upon the author's 

 investigations. A, embryonic cells; colorless plastids (P) shaped 

 like filaments, rods, and granules, indistinguishable from the 

 genuine chondriosomes (C) ; chondriosome-shaped vacuoles (V) 

 looking like canaliculi of Holmgren; Gg, lipide granules 

 (microsomes of other authors) which do not stain with mito- 

 chondrial techniques. Ri, cell at the beginning of differentiation 

 in root; vacuoles enlarging and coalescing; plastids and chon- 

 driosomes unchanged. R2, mature cell of root; a single large 

 vacuole: plastids show vesicles with starch (A) which mito- 

 chondrial techniques do not stain. Fi, cell of leaf primordium; 

 vacuoles enlarging and coalescing; plastids form swellings which 

 increase in size, separate and become chloroplasts. F2, mature 

 cell of leaf; a single vacuole; large chloroplasts easily distin- 

 guishable from the chondriosomes. 



chloroplast, on the one hand and the phanerogams, on the other, 

 in whose embryonic cells no distinction whatever can be estab- 

 lished between the plastids and ordinary chondriosomes. 



