196 N. H. COWDRY. 



markable picture (Fig. 18). They are loaded with a multitude 

 of granules and filaments, some of which appear to be swollen 

 and elongated to a relatively large extent, indicating perhaps im- 

 bibition of lecithin from the surrounding fluid and subsequent 

 incorporation in the mitochondrial substance. It is to be further 

 noted that these enlarged mitochondria are never truly vesicular ; 

 their staining reaction, in some cases, appears to be fainter than 

 that of the definitive mitochondria, which presumably have not 

 approached the nucleus and which are changed to a comparatively 

 minor degree. 



Other plantlets grown on blotting paper saturated with lecithin 

 solution exhibited the same appearance. 



Radicles, of control plantlets subjected to the same treatment, 

 grew vigorously, but the growth of the plumule was abruptly 

 stopped and chlorophyll formation ceased entirely. Compare 

 this with the growth and increased chlorophyll production under 

 the influence of ether. 



This association of lecithin with the enlargement of mitochon- 

 dria is of interest from several points of view. In the first place, 

 Russo ('12, p. 215) claims to have been able to increase the mito- 

 chondria in the oocytes of the fowl through the injection of leci- 

 thin. Unfortunately, however, the technique which he employed 

 is open to criticism on account of the lack of specificity of his 

 staining reactions. In any case, the parallelism between his ob- 

 servations and my own is interesting and may be significant. 

 Moreover, Lowschin ('13, p. 203; '14, p. 269) is credited with 

 the making of artificial mitochondria with lecithin in different 

 salt and albumin solutions, which in some respects resemble true 

 mitochondria very closely. Many other observations might be 

 cited which indicate that mitochondria are allied in composition 

 to substances of the phosphatid group. 



DISCUSSION AND CONCLUSION. 



In considering the effect of various experiments on mitochon- 

 dria we must bear in mind the normal variation. They vary in 

 diameter, length and appearance in the same cell and in different 

 parts of the same root-tip where the cells of the plerome, peri- 

 blem, root-cap, epidermis and meristem each have some peculiar 



