Literary Notices. xxxvii 



is stained, but very intensely, so that it appears quite black in the larger fibers. 

 The deeper layers of the myelin are scarcely at all stained and the axis cylinder 

 is decolorized to a clear yellow which is sharply differentiated from the rest of 

 the fiber. The smaller fibers are more uniformly, but more faintly stained. 



54 iT/. Specimen fixed for ii days in Flemming's fluid, mordanted by 

 Weigert's copper acetate and sodium potassium tartrate 2 hours, followed by 

 half-saturated copper acetate I hour, stained in Weigert's hcematoxylin and de- 

 colorized by the method of Weigert. 



This method here, as after the chrora-acetic fixation, cannot apparently be 

 used exactly as designed by Weigert, i. e. without any decolorizing, but, if 

 properly differentiated with the decolorizer, gives preparations which are very 

 attractive. Though I have not used the method extensively, I think it could 

 with slight further modification be developed into a very valuable method for 

 peripheral nerves. The sections thus far obtained are not so clear, however, 

 as those last mentioned. The histological character of the fibers is about as in 

 No. 46. 



After the experiments above described had been performed my 

 attention was attracted by the somewhat similar series of experiments 

 by Bolton^ in which Weigert sections of human brains were prepared 

 after mordanting only in osmic acid, and also in a variety of metallic 

 salts. Accordingly I instituted a few further experiments to test the ap- 

 plicability of such a procedure with the fish brain, with results which fol- 

 low, partly under the present head and partly under the next one (for- 

 malin fixation). 



55 M. The brain of an adult specimen was hardened four days in Flem- 

 ming's fluid and after paraffin embedding the sections, without further mordant- 

 ing, were stained directly in Kultschitzky's hematoxylin for two and one-half 

 hours at 40° C. They refused to take up the stain at all, showing apparently 

 that further mordanting is essential. 



56 M. The same sections, after thorough washing in water, were treated 

 for four hours with Weigert's hjematoxylin at 40° C. with the same result. 



57 M. Sections prepared as in the last case were mordanted for three hours 

 at 40° C. in two percent, iron alum and stained in Kultschitzky's hsematoxylin at 

 40° for 20 hours. They also refused to take up the stain. 



58 M. Sections prepared and mordanted like the last, but stained for 20 

 hours in Weigert's hasmatoxylin at 40° take up the stain well and when decol- 

 orized in Weigert's fluid yield fairly good preparations, though the stain is feeble. 

 Other sections mordanted for 12 hours cold and stained for five hours give a 

 stronger stain, and yet not wholly satisfactory. 



Suffwiary. — Fluids containing osmic acid give the most perfect 

 fixation of the meduUated nerves. Hermann's fluid is the best of all, 

 and it blackens the nerve sheaths so well that sections mounted directly 

 without further staining are the best that I have secured by any method 



^ Joseph Shaw Bolton. The Nature of the Weigert-Pal Method, Jour. Anat. 

 and Physiol., XXXII, 2, Jan., 1898, p. 247. 



