THE STRUCTURE OF CHROMOPHILE CELLS OF THE XER\OUS SYSTEAL 35 



have acted upon both; but one shows the condition and tlie other does not (as is 

 shown in all the figures). Furthermore, if mechanical injury is the cause of the 

 condition, it is difficult to understand why chromophile cells are so rare in the spinal 

 cord and in the ganglia of the cranial nerves, which are bound down by membranes 

 and which in removal are consequently subjected to greater mechanical injury than 

 the cortex of the brain. 



In order to settle the (luestion the results of intentional mechanical injury 

 brought about by bruising the cerebrum and the spinal ganglia with a blunt instru- 

 ment were studied. It was found that the lesion produced was characterized bj^ 

 the flattening or comj^ression of many cells in the same direction, at right angles to 

 the direction in which the pressure had been exerted. All the cells in the area were 

 uniformly affected. Normal cells were not scattered among them. The injured 

 cells stained intensely, but they did not simulate the chromophiL- cells. The 

 neuropil between them showed marked changes and could readily be distinguished 

 from the neuropil elsewhere in the same section. 



Chromophile cells are not the result of differences in the time or in the degree of 

 fixation. The whole brain is uniformly fixed by the methods of technique emploj^ed. 

 The distribution of chromophile cells is not related to the arrangement of the blood- 

 vessels, which are the avenues of approach of the fixative. Neither do the mito- 

 chondria varj' in number with the vascularity of the region. 



The condition is not due to irregular mordanting with the j^otassium bichro- 

 mate, because complete extraction of the bichromate by prolonged treatment with 

 l)ermanganate and oxalic acid does not essentially modify the appearance of the 

 chromophile cells when the sections are stained. 



Another possibility is that the intense staining of the chromophile cells results 

 from incomplete differentiation. Even if this were the case the differences in the 

 rate of decolorization must be the visible expression of real differences in the cells 

 themselves. I have found, however, that the same differences obtain in undiffer- 

 entiated specimens stained lightly with fuchsin, crystal violet, and iron hematoxylin. 

 I have made a number of experiments to determine whether more complete differ- 

 entiation would bring to light formed mitochondria in cells in which they appear 

 to have been replaced by the amorphous deposit which stains in the same way. 



Specimens were stained in the usual fashion with fuchsin and methyl green and 

 were mounted in balsam. Drawings were then made of chromophile cells which had 

 been stained intensely with the fuchsin and in which no formed mitochondria could 

 be seen. The cover-glass was then dissolved off and the slide was passed down 

 through toluol and graded alcohols to water. It was then r(\stained with fuchsin, 

 differentiated more strongly with the methyl green, mounted in balsam, and 

 examined. The same condition was apparent, except that the homogeneous deposit 

 had a distinctlj' greenish color. The same process was repeated as many as five 

 times with the same cell, increasing each time the extent of differentiation, until 

 the cell stained intensely with methyl green and very little trace of the fuchsin was 

 left; still no formed mitochondria were observed; this was repeated with other cells 

 with the result that in some of them formed mitochondria were brought to light, 

 while in othei-s thev were not. 



