2IO N. H. COWDRY. 



able because a comparatively large amount of the tissue juice 

 is liberated which brings about a troublesome precipitate of the 

 dye and makes it necessary to renew it frequently. In short, 

 plant cells are very hard to handle but the stain is none the less 

 specific. The petals of some flowers (narcissus, sweet pea, freesia, 

 etc.) give very much more satisfactory results than the pea 

 since with them the dyes penetrate more easily. 



I have also tried to stain the living plants in toto by growing 

 them in sand moistened with a strong solution of janus green B. 

 I discovered at once that they react differently to this treatment. 

 Peas were stunted, but grew and flowered without any coloration 

 with the exception of the root hairs and small portions of the 

 epidermis which seemed to be dead. On the other hand, gourds 

 grew vigorously for a time and became intensely stained while 

 growing. They presented a very beautiful appearance because 

 in some of the tissues the dye is reduced to its color base, 

 diethylsafranin, so that the plant is marked off into red and 

 bluish green areas following the distribution of processes of 

 reduction and of oxidation. Cells from the different regions 

 were examined and it was found that the whole protoplasm was 

 stained more or less uniformly and that the mitochondria were 

 not specifically colored. These experiments would seem to 

 indicate that the vital staining of plants with the less toxic azo 

 dyes is full of promise from the point of view of plant physiology. 



This specific comparison of the mitochondria in the pea and 

 in the pancreas has shown that morphologically they are almost 

 identical, save for a slight difference in diameter. No forms are 

 present in the one for which counterparts cannot be discovered 

 in the other. If they could be viewed dissociated from their 

 environment it would be next to impossible to tell which belonged 

 to the pea and which to the pancreas. Microchemically they 

 are identical so far as our imperfect methods go. Similar fixatives 

 preserve them, modify them and destroy them in like fashion in 

 both. Even the experimental error is the same. Finally, and 

 most important of all, they react the same way to the janus 

 green test and to other supravital dyes. Accordingly our provi- 

 sional conclusion can be none other than that the mitochondria 

 in the pea and in the pancreas are composed of precisely the 

 same material. 



