ELIZABETH KINNEY. 



averaging between 3 and 5 micra in length, and about 0.5 micron 

 in diameter. In the more anterior portions of the gland, the 

 mitochondria are found to be shorter, but equally numerous. 

 Mitochondria do not appear to have any direct relation to the 

 cytoplasmic bodies, but the latter are found situated among the 

 mitochondria! filaments. 



Material stained with iron haematoxylin after fixation in 

 either the Champy or Gatenby method exhibits the presence of 

 structures similar in size, shape and distribution to those ob- 

 served with Regaud fixation (Figs. 5, 6). 



2. Middle Region. In the middle region, mitochondria are 

 always present but their shape is somewhat different from 

 that of the mitochondria in the posterior region. A gradual 

 transition may be seen from the long filaments in the secreting 

 region to the shorter rods in the anterior portion of this region 

 (Fig. 7) and finally, in the true reservoir, the mitochondria 

 become shortened to granules or spherules. The latter have the 

 properties of mitochondria but are somewhat larger in diameter 

 than the mitochondrial granules. It is not probable that the 

 larger spherules represent secretion since in appearance, they 

 more nearly resemble mitochondria than secretion bodies. 



The distribution of mitochondria is fairly disperse through- 

 out all parts of the cell, but with a tendency to be more abundant 

 toward the lumen. No definite orientation can be distinguished 

 in the longer rods (Fig. 12). 



3. Anterior Region. Bodies taking a stain characteristic of 

 mitochondria are present in the anterior region, but these are 

 always granular and arranged with little definite order (Figs. 



, 9). 



4. Critical. From tin- preceding observations, it is seen that 

 mitochondria are present in the cytoplasm throughout the entire 

 extent of the tubule. Their shape and to a less extent their 

 number varies, however, in the three arbitrary divisions of the 

 gland. Cowdry ('24, p. 318) suggests that mitochondria may 

 serve to some extent as indicators of secretory polarity- In the 

 case of silk secretion, it seems that this is truly the- conclusion 

 to be drawn. Secretion can be traced from the cell into the 

 lumen, and mitochondria appear to be streaming toward the 



