2I 4 



N. H. COWDRY. 



progressively more resistant to acetic acid in this process of 

 plast formation. Similarly in the spermatogonia of certain 

 animals the mitochondria are diffusely arranged (Fig. 22) ; in 

 the spermatocytes they approach the nucleus (Fig. 23) and 

 become so closely applied to it that investigators have been 

 deluded into thinking that they actually originate from it. In the 

 later stages of spermatogenesis they leave the nucleus (Fig. 24) 



19 



20 



FIGS. 19, 20 and 21. Meristem and young and old cortical cells of the pea fixed 

 in formalin and picric acid (Regaud III) and stained with iron hematoxylin showing 

 primary diffuse arrangement of mitochondria, secondary condensation about the 

 nucleus and final even distribution throughout the whole cytoplasm. (1,500 

 diameters.) 



becoming more resistant to acetic acid as Regaud ('08, p. 662) 

 has shown. Indeed the parallelism is very close. Other in- 

 stances might be cited. 



In plant cells one rarely finds a condensation of mitochondria 

 in the peripheral cytoplasm though it is frequently met with in 

 animal cells. It is particularly manifest in certain stages in the 



