IQO N. H. COWDRY. 



well shown in the figure. The mitochondrial filaments near the 

 nucleus show a tendency to become swollen and to stain more 

 intensely with iron hematoxylin throughout their whole length 

 or in certain restricted areas, as contrasted with those in the 

 more peripheral parts of the cell. 



The vacuoles occupy a considerable portion of the cytoplasm 

 and sometimes contain a few mitochondria in their interior. 

 These mitochondria, which are always darkly stained, enlarge 

 into spherules of different sizes. 



The effect of different experimental conditions was studied as 

 follows : 



OBSERVATIONS. 



i. Ccntrifuging. 



Plantlets were centrifuged for one hour with results as indi- 

 cated in Fig. 2. The nucleus appears to have been thrown 

 against the cell wall and is in some cases quite flattened. While 

 a thin layer of protoplasm remains everywhere in contact with 

 the cell wall, the greater portion of it has assumed a portion be- 

 tween the nucleus and the vacuole. It is of shreddy consistency 

 and contains enlarged mitochondria. 



I have seen no indications of the existence of a difference in 

 specific gravity between the mitochondria and the protoplasmic 

 ground substance in the cortical cells of the pea radicle as de- 

 scribed by Faure-Fremiet ('13, p. 602) in Ascaris. Key, 1 using 

 also the centrifuge method, failed to detect any difference in the 

 specific gravity of the mitochondria and the protoplasmic ground 

 substance of nerve cells. On the other hand Beckwith ('14, p. 

 216) succeeded in separating the cytoplasmic constituents in the 

 eggs of Hydractinia into three layers : first, the oil cap, second, a 

 layer of clear protoplasm and, lastly, a mingled mass of yolk 

 and mitochondria. These observations indicate, probably, the 

 existence of variations in the fluidity of the ground substance, 

 not of differences in the mitochondria themselves. 



2. Plasmolysing Agents. 



Normal plantlets of two days growth were placed so that their 

 radicles were immersed in a 20 per cent, solution of cane sugar 



i Quoted from E. V. Cowdry ('18, p. 84). 



