2O6 N. H. COWDRY. 



PLATE III. 



FIG. 13. The cell figured is from the inner cortex of the same section as 

 Fig. 12. Mitochondria here are almost normal. Filaments are seen with no 

 tendency to approach the nucleus and contrasting strongly with their altered 

 appearance in the middle and other layers. 



FIG. 14. Plerome cell from a radicle 6 mm. long and exposed to the same 

 confined air-space for two days. Mitochondria have, in many cells, completely 

 disappeared. There are, however, in the cells of the plerome a few lightly 

 stained rods and granules, with some intensely stained, enlarged plast-like 

 bodies. The nucleus shows many strongly stained granules at its periphery. 



FIG. 15. Cell from the cortex of a plantlet exposed to the vapor of chloro- 

 form, for 2.y 2 minutes in a Petri-dish of 100 c.c. capacity. The radicle is 

 about 7 mm. long. Mitochondria have disappeared leaving no trace except a 

 few lightly stained spherules and dark blotches in the protoplasm. The vac- 

 uole is filled with a comparatively darkly stained coagulum. 



FIG. 1 6. Cell from a radicle 10 mm. long exposed to the vapor of ether for 

 7 minutes under the same conditions as Fig. 15. Mitochondrial granules and 

 rods are very distinct but are irregular in outline. The protoplasm has greatly 

 changed in consistency and appearance. 



FIG. 17. The plantlet, grown normally, was placed so that its radicle was 

 immersed in a 10 per cent, solution of glycerine for 18 hours. A radicle 7 

 mm. long was selected. The cells show a complete disappearance of mito- 

 chondria leaving no trace except indistinct darker staining areas in the 

 protoplasm. 



FIG. 1 8. Plantlets grown normally were placed so that their radicles were 

 in contact with a one per cent, solution of lecithin for one day. A radicle 25 

 mm. long was selected. Mitochondria exhibit a very marked increase in num- 

 ber and size. 



