198 



N. H. COWDRY. 



ence with one or the other, seldom with both. It is essential 

 that the two should be compared side by side. 



I have chosen for my experiments the cells of the radicle of 

 the pea and the acinus cells of the pancreas of the mouse on 

 account of the close resemblance of their mitochondria. The 

 general appearance may be seen by reference to Figs. I and 2. 

 Morphologically the mitochondria would seem to be identical 

 in the two; but in reality this is not the case, for I have examined 

 them very carefully with a high magnification (3,500 diameters) 

 and I find that they are, on the whole, slightly longer and thicker 



* ^* v 



c^ 'X, 



i i i i 1 i i i i 



FIG. 3 Selected mitochondria from cells of pea radicle prepared by Regaud IVB 

 to show the extent and limits of the polymorphism. (3,500 diameters.) 



in the pancreas. I have made detailed drawings to scale of 

 selected mitochondria from both. This can be done with con- 

 siderable accuracy by making use of a good camera lucida, 

 with appropriate illumination, and a sharply pointed pencil. 

 The results are illustrated in Figs. 3 and 4. Filaments, rods and 

 granules predominate. Branching filaments, networks, spherules 

 and so on are rarer, but occur in both. In fact no form, however 

 bizarre, is to be found in the one for which a counterpart cannot 



