352 MARGAEET R. LEWIS AND WARREN H. LEWIS 



is probably no relation between the movement of the cell and 

 the movement of the mitochondria, for the cell processes change 

 their position so slowly that there is often no noticeable change 

 for several hours, while the mitochondria change position rapidly 

 and continually. 



Occasionally in a syncytium of cells a mitochondrium may 

 pass over the cytoplasmic bridge from one cell to another (fig. 

 5 g) . In some cases a mitochondrial thread may pass over the 

 bridge into another cell and later return. 



What is it that governs the arrangement of the mitochondria? 

 Is it the shape of the cell, the influence of the central body or 

 of the nucleus, the internal structure of the cytoplasm, or do 

 the metabolic activities of the cell govern the size, shape and 

 arrangement of the mitochondria? 



Shape of mitochondria 



The mitochondria exhibit extraordinary diversity of form often 

 in the same preparation, even in adjoining cells of the same 

 type (figs. 4, 5). Not infrequently a single cell may contain 

 mitochondria of diverse shapes (fig. 5 e) . These different mito- 

 chondrial shapes may be more or less localized in different parts 

 of the cytoplasm (fig. 5 e) or may be more or less mixed together 

 (fig. 4 b) . The extraordinary diversity in form of the mito- 

 chondria shown by cells of the same type lying side-by-side in 

 the same preparation is sometimes very striking. Such differ- 

 ences occur in the young growing cells after division, in older 

 resting cells and even during the various stages of mitosis. 

 Again, we may find in the same preparation groups of cells 

 in one part of the growth, that have very similarly shaped 

 mitochondria, while in another part practically all of the cells 

 may have quite differently shaped mitochondria. In such prep- 

 arations all gradations in shape and size, from minute granules 

 to larger and larger ones, or from rods to threads of various 

 lengths, or threads and networks, etc., can be seen in adjoining 

 cells of the same type or even in the same cell. Just as the 

 fixed preparations show such gradations, we find that all sorts 



