194 N - H - COWDRY. 



tions were more marked in the outer cortical cells, which present 

 complete chondriolysis, than in the deeper ones. In the middle 

 cells of the cortex the mitochondria exhibit great polymorphism 

 as illustrated in Fig. 12, rings, spheres, rods, granules, and dumb- 

 bell shaped forms being visible. Variations in staining reaction 

 are of common occurrence and the mitochondria have lost their 

 tendency to cluster about the nucleus. The inner cells, on the 

 contrary, contain the usual thin filaments with some plast-like 

 forms (Fig. 13). 



When the same treatment is continued for two days the altera- 

 tions become still more pronounced. The cells of the plerome 

 are illustrated in Fig. 14. The mitochondria are very scanty, the 

 protoplasm shows signs of disorganization and the nuclei are 

 loaded down with a granular deposit. The controls from this 

 series all died so that we are unquestionably dealing with death 

 changes. 



These observations seem to be in accord with the view first 

 advanced by Kingsbury ('12, p. 46) and supported by Mayer, 

 Rathery and Schaeffer ('14, p. 619) that the mitochondria play 

 an active part in protoplasmic respiration. 



9. Chloroform. 



Plantlets were exposed to the vapor of chloroform, in a cov- 

 ered Petri-dish of 100 c.c. capacity for 45 seconds without the 

 mitochondria undergoing any marked alterations. Continuing 

 the same treatment for 2^/2 minutes, however, brings about dis- 

 tinct changes (Fig. 15), only a thin layer of protoplasm remain- 

 ing intact, in which may be distinguished a few scattered mito- 

 chondria with very vague outlines. The vacuole is filled with an 

 intensely stained granular deposit without any trace of mito- 

 chondria. Plasmolysis is fairly advanced. This treatment re- 

 sulted in the death of the root tips of the control plantlets. It is 

 interesting to compare this condition to the well known immunity 

 of mitochondria to the action of chloroform after fixation. 



10. Ether. 



On exposure to the vapor of ether, under the same conditions, 

 for 3^/2 minutes no distinctive changes were observed in the 



