38 A. T. RASMUSSEN 



ous tissue is extremely limited. Strongman ('17), who inves- 

 tigated the results of muscular fatigue in white mice, found no 

 constant variation due to such activity, except possibly a tendency 

 toward a clumping together of the mitochondria in the fatigued 

 animals. This effect was especially apparent at the base of the 

 large dendrite of Purkinje cells in the cerebellum. Luna ('13) 

 found that shortly after cutting a large peripheral nerve trunk 

 in the toad the mitochondria of corresponding ganglion cells lost 

 their regular distribution, increased in size, and showed an 

 increased affinity for the iron-haematoxylin stain. In more 

 advanced stages of degeneration the mitochondria disappeared 

 entirely. Busacca ('15) found that stimulation of the eye of the 

 toad with light caused a decrease in the number of mitochondria 

 in the pigment cells of the retina. 



Earlier observations on the behavior of neurosomes — the 

 smaller of which have been shown by E. V. Cowdry ('12) to be 

 mitochondria — made by Levi ('96), Motta-Coco and Lombardo 

 ('03), and by Scott ('05) indicate an increase in the number of 

 these fuchsinophil granules during activity in nerve cells. Scott 

 suggests, however, that such changes may be only apparent, since 

 the entire cell is not examined, but merely the cell body, while 

 the most important point of activity is at the nerve endings. 



On the whole, it appears that mitochondria of nerve cells are 

 comparatively resistant to conditions associated with normal 

 processes. 



In many pathological tissues (for literature see McCann, '18, 

 and E. V. Cowdry, '18) mitochondria often show marked altera- 

 tions even in early stages, and yet, according to McCann ('18), 

 in experimental poliomyelitis the mitochondria persist in normal 

 number in proportion to the cytoplasm in cells not only where the 

 Nissl substance has disappeared, but also in the latest stages of 

 neurophagocytosis. 



Having seen nothing on record concerning mitochondria in 

 nerve cells during hibernation, it seemed desirable to investigate 

 the influence of profound dormancy in mammals, such as is char- 

 acteristic of hibernating marmots, notwithstanding the fact that 

 changes during lethargy in the Nissl granules, which are consid- 



