N 



Guilliermond - Atkinson 



110 



Cytoplasm 



..-».. 



ill 



P'V-v ill 



merit (Fig. 78, B, C) and then there can be followed in these cells 

 (Fig. 78, D-F) a differentiation of large rhodoplasts from some 

 of the elements of the chondriome. In the mature carpospores 

 (Fig. 78, G, H) there are found fairly large, well differentiated, 

 disc-shaped rhodoplasts. 



In the Characeae, Mangenot found small chloroplasts and 

 chondriosomes in the apical cells but in the oosphere there is no 

 chlorophyll. In the cells which give rise to the oosphere, Mange- 

 not observed a regression of the small chloroplasts. They lose 

 their chlorophyll and are transformed into mitochondria or short 

 rods which can not be distinguished in the young oospheres from 

 the inactive chondriosomes. In the course of development of the 

 oosphere, some of the mitochondria and rods representing the 

 former chloroplasts, elongate and take on the shape of typical 



chondrioconts, whereas the inactive 

 chondriosomes persist in the form 

 of mitochondria. The chondrioconts 

 then elaborate numerous starch 

 grains in the usual way. They cor- 

 respond therefore to amyloplasts. 



Information on the development 

 of the plastids is still scarce in the 

 bryophytes. It has already been 

 seen that Rudolph, Scherrer, Sape- 

 HiN, and MOTTIER believed that 

 chlorophyll persists in these plants 

 in all stages of development. They 

 state that bryophytic cells always 

 contain chloroplasts and chondrio- 

 somes at the same time. The fact 

 is well demonstrated for Anthoceros 

 but is questioned for the other bryo- 

 phytes. Whereas P. A. Dangeard, 

 P. Dangeard, Gavaudan and Weier 

 tend to confirm it, Alvarado, Sen- 

 JANINOVA, MOTTE and Chalaud op- 

 pose it and believe that the chloroplasts are derived from the 

 chondriosomes. Alvarado has stated that in young paraphyses 

 of Mnium cuspidatum there are no chloroplasts but only chondrio- 

 somes of which some afterwards become transformed into chloro- 

 plasts. According to Motte, most mosses contain in the apical 

 cell of the stem both small lenticular chloroplasts and chondrio- 

 somes, while in some species {Grimmia crinita) only chon- 

 driosomes are found, a part of which develop into chloroplasts in 

 cells arising by division from this apical cell. Motte described a 

 regression of chloroplasts in the sperm mother cells. In the forma- 

 tion of these cells, the chloroplasts lose their chlorophyll and be- 

 come transformed into long chondrioconts. These fragment to 

 form granules that it is impossible to distinguish from the chon- 

 driosomes, which are coexistent with them. According to Motte, 



'I 



B 



Fig. 79. — Chara fragilis. Develop- 

 ment of the chondriome in the egg. A, 

 young egg. B, beginning of differentia- 

 tion. C, later stage, appearance of 

 chondrioconts. D, mature egg; chon- 

 drioconts forming starch. E, detail of 

 (D). 



