MITOCHONDRIA IN PLANT AND ANIMAL CELLS. 



213 



filamentous mitochondria are usually distributed parallel to the 

 long axis; which calls to mind the arrangement of mitochondria 

 in gland cells, nerve cells, muscle cells and others. In the 

 serous cells of the parotid they are heaped up in the proximal 

 region next the basement membrane and remote from the lumen 

 (Fig. 16). Where the polarity is reversed as in the thyroid 

 (Fig. 17), the mitochondria are also reversed; while in the epi- 

 thelial cells of the intestine, they are condensed at both poles 

 (Fig. 18). This, Champy ('12, p. 109) thinks, is indicative of a 

 double polarization for adsorption and for secretion. Corre- 

 sponding condensations have not been recorded in plant cells. 



FIG. 16. Serous cells of parotid of mouse with proximo-distal polarity, as 

 represented by the arrow, B. M. being the basement membrane. (1,500 diameters.) 



FIG. 17. Thyroid cells (after Bensley, '16, p. 55) with reversed polarity, disto- 

 proximal, in the direction of the basement membrane. 



FIG. 18. Intestinal epithelial cells with double polarity, mitochondria being 

 accumulated at both poles. (1,500 diameters.) 



Mitochondria, however, group themselves about the nucleus 

 in both plants and animals. In the early meristem of plants, 

 generally, mitochondria are found indifferently distributed in 

 the protoplasm (Fig. 19). They soon approach and appear to 

 come into actual contact with the nucleus (Fig. 20) in which 

 "position they enlarge and form plasts which migrate away from 

 the nucleus and become distributed more or less evenly in the 

 surrounding protoplasm (Fig. 21). Guilliermond has repeatedly 

 described this migration. I find that the mitochondria become 



