34 THE STRT^CTURE OF CHROMOPHILE CELLS OF TIIIO NERVOUS SYSTEM. 



quite numerous in the cerebellar cortex. The Purkinje cells are j^articularly liable to 

 show this condition. They are infrequent in the medulla and they scarcely ever occur 

 in the spinal cord, in the sjjinal ganglia, or in the sensory ganglia of the cranial nerves, 

 as, for example, the Gasserian ganglion. In other words, this remarkable condition 

 of the nerve-cell is more prevalent in the higher centers than in the lower ones. This 

 is particularly true of chromoi)hile cells in advanced stages of chromoi)hilia. 



The (juesiion at once arises as to whether these changes in the api)earance of 

 the cells are indicative of real alterations in the cells themselves or whether they are 

 merely the result of the treatment to which they have been subjected. 



Unfortunately it was found impossible to confirm these observations by the 

 study of unstained, living cells by reason of the difficulties met with in attemi)ts to 

 i.solate the cells without injuring them. Attemi)ts to stain the mitochondria in 

 living cells by injecting a solution of janus green into the brain through the blood- 

 vessels did not yield satisfactory results because the janus green was almost immedi- 

 ately reduced, first to the leucobase, and then to the red diethylsafranin, by the 

 reducing action of the brain-substance and the absence of an adeciuate supi)ly of 

 atmospheric oxygen, so that observations could not be made. Pure oxygen was 

 bubbled through the janus-green solution while it was being injected, in the hope that 

 the reduction of the janus green might thus be retarded, but without success. 

 Attempts to tease out individual cells in the nervous system and to stain them by 

 simple immersion in the janus-green solution resulted, of course, in a coloration of 

 the mitochondria, but it was on the whole unsatisfactory on account of the unavoid- 

 able injury to the cells. Consequently I have had to rely solely upon the study of 

 fixed material. 



The results obtained with the fuchsin-inethyl green method and with the Cajal 

 technique have been confirmed by the detailed examination of material stained by 

 the Benda method, the Altmann method, and with iron hematoxylin. Chromophile 

 cells are, I think, not artefacts due to alcohol fixation, as Barker (1899, p. 124) 

 supposes, because I have observed them in tissues fixed in a great variety of fluids 

 not containing alcohol. Moreover, Flesch (1887, p. 197) found years ago that they 

 could be identified in the fresh, unstained condition as well as in tissues stained 

 vitally with methylene blue. 



The fact that the chromoi^hile cells are very abvmdant in the superficial layers 

 of the cortex would at first seem to indicate, as some investigators belie\-e, that they 

 are artefacts due to mechanical manipulation. The clusters of chromophile cells 

 are sometimes cone-shaped, with the base on the surface of the cortex and the apex 

 of the cone extending inward.s, which looks as if they might have been produced by 

 pressure from without which radiated inwards. But i.solated clumps of chromophile 

 cells occur in deeper parts of the brain, which can not be explained in this way. 

 Moreover, a number of other facts seem to be incompatible with this view. In the 

 first place, since all the brains were fixed, before removal, Ijy the injection of the 

 fixative through the bloorl-ves.sels. it follows that there could be no mechanical 

 injury until after fixation. The invariable occurrence of unaltered cells, side \>y side 

 with the chromophile cells, is hard to explain on the basis of mechanical injury, 

 because whatever pressure had been brought to bear upon the tissue must necessarily 



