342 NORMAN CLIVE NICHOLSON 



heretofore have ekided the grasp of neurologists. One would 

 naturally inquire first into those diseases in which chemical 

 analysis has revealed a disturbance in the lipoid content, particu- 

 larly general paralysis since Koch and Mann ('09) have detected 

 a destruction of the brain phosphatides in this condition and there 

 is a good deal of evidence that the mitochondria are, themselves, 

 closely related to phosphatides. 



Before concluding I w^ant to express mj' deep appreciation to 

 Dr. E. V. Cowdry for his friendly interest and encouragement. 



SUMMARY 



There are qualitative differences in the mitochondrial content 

 of certain types of nerve cells in the brains of white mice. The 

 variation in morphology between cells of different variety is often 

 quite pronounced. Filamentous mitochondria are the most 

 common form met with in the cells of the central nervous sys- 

 tem. They are particularly apparent in large anterior horn 

 cells (fig. 1) and in the large cells of the reticular formation (fig. 

 11). Rod-like and granular mitochondria are rarer. They are 

 characteristic, however, of the cells of the mesencephahc nu- 

 cleus of the fifth nerve (fig. 5) as well as of the cells of the Gas- 

 serian gangUon (figs. 6 and 7). The cells of the nucleus of the 

 corpus trapezoideum (fig. 2) may be distinguished by their large, 

 swollen block-like mitochondria. 



There is also, in the majority of cases, a variation in the form 

 of mitochondria in different parts of the same cell. For instance, 

 they are usually more granular in the vicinity of the nucleus 

 than in the peripheral parts of the cytoplasm, and in the pro- 

 cesses. In the processes they are invariably rod-like or fila- 

 mentous. This is shown in most of the drawings but it is par- 

 ticularly well illustrated in figures 1, 5, 9, 10, 11 and 12. The 

 cells of the nucleus of the trapezoid body constitute a special 

 case because in them the mitochondria always occur in the form 

 of long blocks in the peripheral cytoplasm in sharp contrast to 

 the minute granular and rod-like mitochondria in the imme- 

 diate neighborhood of the nucleus. The mitochondria occur not 



