42 A. T. RASMUSSEN 



RESULTS 



A description of the mitochondria of the nerve cells in this par- 

 ticular animal is unnecessary since they are essentially as de- 

 scribed in other vertebrates by E. V. Cowdry ('12, '14), Busacca 

 ('13), Nicholson ('16), and others. Suffice it to say that in the 

 central nervous system they are usually granular near the 

 nucleus and tend to become short rods more peripherally and long 

 filamentous in the base of the processes and out in the dendrites 

 and axon proper. In the spinal ganglion they are glandular or 

 very short rods rather uniformly distributed throughout the cell 

 body except in places where there is an accumulation of lipoid. 

 In such regions the mitochondria tend to be excluded. This 

 reciprocal relation between lipoid and mitochondria in spinal gan- 

 glion cells has been noted especially by Cowdry ('14) in a number 

 of species of vertebrates. In no case, however, was there much 

 lipoid, and in spinal ganglia, where most often encountered, 

 only two or three cells in a section through an entire ganglion 

 would contain any obvious lipoid by the method employed. 

 But since there are innumerable gradations between granules 

 and filaments, it was not practicable to determine any variation 

 in the different types of mitochondria upon any quantitative 

 basis. General examination, however, indicated no variation in 

 shape or size characteristic of either particular individuals or of 

 any of the three stages. 



Many of what appeared to be rods are undoubtedly merely 

 rows of two or more granules so closely packed that it is not 

 possible to distinguish the separate components with the avail- 

 able apparatus. In imperfectly fixed tissue mitochondria are fre- 

 quently clumped into larger masses which are clearly not repre- 

 sentative of the normal condition. To what extent this occurs 

 in the case of the best fixation is difficult to say. The long fila- 

 ments in the axon and dendrites and in the cell body at th^ base 

 of these processes are undoubtedly continuous filaments, since 

 they are never seen as rows of granules and are always elongated 

 continuous bodies even in the most superficial fibers in a block and 

 next to large vessels where the fixation has been instantaneous 

 while the tissue was still warm. Too much reliance cannot be 



