36 TITK STRrCTlRE OF CHHOMOPHILE CELLS OF THE XERVOl'S SYSTEM. 



Similar experiments were performed with individual cells stained a homogejieous 

 black color with iron hematoxylin. The results obtained are easier to interpret 

 because the differentiator, iron alum, does not itself color the tissue like the methyl 

 green. This advantage is counterbalanced by the fact that both the mitochondria 

 and the Nissl substance stain in the same way and it is often difficult to distinguish 

 between them. In many cases, particularly in slightly undifferentiated specimens, 

 the extraction of the stain from chromophile cells l\v further differentiation brought 

 to light a varial)le number of formed mitochondria. Moreover, it is worthy of note 

 that the chromophile cells in the cerebral cortex are the last to become decolorized 

 and that the differentiation occurs with unequal rapidity in different parts of the 

 cell, thus indicating that the homogeneous deposit is not present in the same con- 

 centration in all jxirts of the cell. 



The end-result of this experimentation is that chromophile cells, particularly 

 those in advanced stages of the condition, contain a diffuse deposit, which stains in 

 a tj'pical way with all mitochondrial dyes, and which is probably formed by the 

 solution of some of the mitochondria in the cell. 



The condition is not due to technique and it is not associated with a visible 

 pathological change on the part of the animal. 



All the mice emjjloyed were apparently normal. They ate well and showed 

 no signs of sickness. They were killed with chloroform, and it may at once be said 

 that the changes are not due to acute chloroform poi.soning, because animals killed in 

 other ways, bj^ decapitation, for example, showed the same condition. The mice 

 were not excited, or disturbed or exercised in any unusual way before they were 

 killed. A careful autopsy of each mouse was made to make sure that it was quite 

 normal. Fome were found to contain a parasite, present in the cysticercus stage 

 in the liver; these were invariably discarded. The chromophile cells were found in 

 mice of both sexes in almost all seasons of the year. They were found in mice 

 varying in age from 25 days to adults, so that thej^ can not be regarded as an expres- 

 sion of senility. It was thought that they might occur in consequence of abnormal 

 conditions due to ca{)tivity. In order to settle this point a wild field-mouse was 

 captured alive and in good condition and its brain was prepared in the usual way. 

 It, also, showed chromophile cells. 



An apparently analogous partial solution of mitochondria was observed in 

 liver-cells ])oisoned with phosi)horus by ]\Iayer, Rathery, and Schaeffer (1914, 

 1). 609). Accordingly, ^^'. J. M. Scott tried the effect of ex])erimental i)hosphorus 

 poisoning on the nervous system of white mice. The chromophile cells were 

 apparently entirely unaffected and a solution of mitochondria was not brought 

 about. Dr. Bensley made the interesting suggestion to me that this jiartial solu- 

 tion of mitochondria in chromoi)hile cells might be due to a swing of the reaction 

 in them toward the acid side, with the liberation of free fatt}' acids. I therefore 

 made some preliminary experiments on acidosis in mice ])ro(luced by the sub- 

 cutaneous injection of dilute hydrochloric acid, all of which yielded negative results 

 as far as the chromophile c(>lls were concerned. I have, further, f(jund that slight 

 exercise does not alter the api)earance of the chromophile cells in the brains of white 

 mice to any noticeable extent. 



