The American Naturalist. [August, 
!. B, a more advanced stage ; the microgonidium has fastened itself 
: body of the macrogonidium, and its substance begins to penetrate 
MICROSCOPY. 
Kultschitzky's^ Methods of Staining the Central Nervous 
System. — The tissue, having been hardened in Miiller's fluid, or 
preferably in Erlichi's fluid, imbedded in celloidin, and sectioned, is 
allowed to remain in the stain from a few minutes to several hours. 
The first solution of hsematoxylin is made as follows : 
Boracic acid (saturated sol.) 20 ccm. 
Water (distilled) 80 ccm. 
The hematoxylin should be dissolved in a small quantity of alcohol, 
and then mixed with the boracic acid and water. The resulting fluid 
will at first be yellow, but in two or three weeks it will change to a 
dark yellowish red. Before using, the solution should be acidulated 
with a small quantity of acetic acid, two or three drops in a watch-glass 
being sufficient. After the sections have been in the stain fifteen 
minutes, the medullated fibres are found to be of a dark violet or blue, 
while the other elements are of a light yellow or yellowish red. If the 
sections are allowed to remain longer, from eighteen to twenty-four 
hours, an intense differential stain results. 
1 Edited by C. O. Whitman, Clark University, Worcester, Mass. 
