Literary Notices. xliii 



This in general I confirm, and also agree with him in finding that 

 other besides nerve tissues may take up and retain the dye, such as 

 blood corpuscles, and the nuclei and especially the nucleoli of nerve 

 cells. The illustrations which he gives of fibers mordanted in chrome 

 alum and in osmic acid (his Fig. 3) show that only the outer zone of 

 the myelinic sheath is stained, the general effect being similar to the 

 Weigert's specimens which I prepared after fixation in Flemming's 

 fluid and mordanted in copper (e. g. No. 53), though it should be 

 noted that all his figures show that the fibers were very badly fixed in 

 his preparations. The differences in the intensities of stain and colors 

 of the nerve sheaths in Bolton's preparations he attributes to the differ- 

 ences in the mordants and in this he is doubtless in the main correct, 

 for he employs only one kind of stain (the acid hsematoxylin) and only 

 one mode of decolorizing. 



Now, the failure of any tissue to stain by the Weigert process may 

 be due either (i) to the fact that it does not take up the th« mordant 

 and hence does not form the lake, or (2) to the fact that the lake 

 formed is there more readily oxidized than the other tissues which re- 

 sist the decolorizer. The first point is emphasized by Bolton — unduly 

 so, as it seems to me. He says, "Just as fine glass threads included 

 in a web would not stain, so nearly the whole of the fibers in the body 

 excepting those belonging to the neurons, do not stain owing to 

 the fact that they refuse the mordant and consquently the lake." But 

 in my experience — and this applies especially to sections contain- 

 ing general as well as nervous tissues — as a rule either the whole sec- 

 tion refuses to stain or all of the tissues take it up intensely, and with 

 the slower methods of decolorizing it is clear that the stain is not merely 

 upon, but is in the tissue elements. It must be admitted that all of 

 these non-nervous tissues, except the blood corpuscles, stain black, not 

 blue, and it may well be that they do not form the same kind of a lake 

 as the myelin of the nerve sheaths. But this applies also to the axis 

 cylinders and to the muscles, in both of which, I infer, Bolton considers 

 that a true lake is formed. The fact that some mordants refuse the acid 

 stain but under the same conditions take up the alkaline stain and con- 

 versely, leads me to believe that a failure to stain may quite as often re- 

 sult from a chemical peculiarity of the tissue after it is mordanted as 

 from a refusal of the mordant 



And this leads to the second point. If the lake is formed, what is 

 it which determines whether it will be more rapidly oxidized in one tis- 

 sue than in another? Bolton believes, apparently, that this condition 

 is simply the permeability of the tissue, "the parenchymatous part of 



