MITOCHONDRIA VARIATIONS IN NERVE CELLS 335 



does not seem to hold, for instance, the shape of the cells of the 

 corpus trapezoideum (fig. 2) and the cells of the corpus striatum 

 (fig. 8) is somewhat similar, yet the mitochondria in them are 

 quite different. An inspection of the cells of the mesencephalic 

 nucleus of the trigeminal nerve (fig. 5) and of the large and small 

 cells of the Gasserian ganglion (figs. 6 and 7) shows that the mito- 

 chondria are rod-like or granular when present in great abun- 

 dance (which would agree well with Dubreuil's hypothesis to be 

 mentioned subsequently). I have not observed any change in 

 the nucleus, or in the nucleoli, or in the Nissl substance, or in- 

 deed in any other cell structure which runs parallel with the 

 above mentioned variations in mitochondria and which might 

 offer a possible explanation of them. I have observed mito- 

 chondria in the surrounding cell processes but am unwilling to 

 state that they actually occur between the cells themselves 

 (that they are intercellular). 



I have not found mitochondria with the bleb-like swellings, 

 which are so common in secreting cells; or in networks. (All 

 the net-like formations observed are illusory, being due to 

 superposition of individual filaments, which can usually be re- 

 solved by careful focussing.) Neither have I seen them swell 

 up to form vacuoles with clear centers, and there is no evidence 

 of an agglutination of mitochondria as occurs in pathological 

 conditions (Scott '16, p. 249). I should therefore feel that the 

 occurrence of such mitochondria was evidence of pathological 

 change. 



Microchemical variations. In the inspection of a large amount 

 of material a certain number of brains were studied, which were 

 for some reason poorly fixed, and it was noted that in these, 

 certain groups of cells contained mitochondria while others did 

 not. An instance in point is that of a brain in which it was ob- 

 served that, while all the cells of the mesencephalic nucleus of 

 the trigeminal nerve contained their normal complement of 

 mitochondria, the neighboring cells of the locus coeruleus, scat- 

 tered among them were found to be devoid of mitochondria. 

 In order to ascertain whether there were differences in the 

 solubility of mitochondria beyond chance variations, the follow- 

 ing experiment was carried out. 



