STUDIES ON MITOCHONDRIA IN PLANT CELLS. 



mitochondria. After exposure for seven minutes the mitochon- 

 dria in the cortical cells are seen to be shrunken and of irregular 

 outline, and to be darkly stained (Fig. 16). Peculiar, irregular, 

 darkly staining masses also appear in the nuclei which are diffi- 

 cult to interpret. The protoplasm has changed in consistency in 

 the cells, but in those of the early meristem and root-cap it is 

 shrunken and stained uniformly and intensely in these prepara- 

 tions, so that the internal structure is difficult to make out. This 

 is not due to incomplete differentiation. The cell walls in these 

 regions seem to have undergone partial fragmentation. 



Controls subjected to the same ether treatment and afterwards 

 placed on damp absorbent cotton grew vigorously with the plu- 

 mule much greater than in the case of other peas sprouted at the 

 same time which had not been treated with ether. According to 

 Jost ('07, p. 195) weak etherization accelerates respiration while 

 strong etherization inhibits it, by killing the cells. It will be seen 

 that growing the plantlets in lecithin has the reverse action in 

 stopping the growth of the plumule abruptly and in inhibiting 

 chlorophyll production. 



The mitochondria are if anything less affected by 7 minutes in 

 ether vapor than by 45 seconds exposure to vapor of chloroform. 



n. Glycerin. 



Plantlets were, as usual, sprouted normally and then placed in 

 a 10 per cent, solution of glycerin in tap water for 18 hours. This 

 treatment brings about a complete chondriolysis of all the mito- 

 chondria in the root tip (Fig. 17) and may be compared with 

 the effect of extreme heat (Fig. 7) and of restricted air space for 

 two days (Fig. 14), though the condition of the ground sub- 

 stance is somewhat different in these conditions. None of the 

 controls survived. 



12. Lecithin. 



Plantlets were placed so that their radicles were in intimate 

 contact with sphagnum moss, thoroughly soaked with a I per 

 cent aqueous solution of lecithin, for 24 hours. (The lecithin 

 used was a pure variety obtained from Dr. Levene of the Rocke- 

 feller Institute.) The cells in these preparations present a re- 



