OLFACTORY CENTERS IN TELEOSTS 179 
MATERIAL AND METHODS 
_ The material used consists of the following eighty-three series 
of sections of the carp brain. 
I. Wewgert method 
Inasmuch as the method used varies somewhat from that usu- 
ally followed, and since it is very successful, it will be briefly out- 
lined here. The fish are killed in a mixture of ether and water, the 
brain removed immediately and placed in 4 per cent formalde- 
hyde for at least forty-eight hours. It is then washed in running 
water for a few hours and placed in Miiller’s fluid at a tempera- 
ture of 40° C. for from eight to fourteen days. The fluid is 
changed every second day during this period. The brain is next 
washed, dehydrated, cleared in carbol-xylene and embedded in 
paraffine. After the removal of the paraffine from the mounted 
~ sections the slides are placed for twelve hours in a half-saturated 
solution of copper acetate, stained three to four hours in Wei- 
gert’s hematoxylin, and differentiated in 24 per cent potassium 
ferricyanide with the addition of 2 per cent borax. Pal’s 
modification was tried but rejected, as it was found that sections 
on the slide could not be evenly differentiated; moreover, the 
method outlined gives rather better results for the work in ques- 
tion, as it brings out the unmedullated tracts and the cell groups, 
which the Pal modification does not. There were stained accord- 
ing to this method: 
Two series transverse sections of the entire brain. 
Two series sagittal sections. 
Two series frontal sections. 
Six series through the olfactory bulbs and crura. 
All of these were from carp 35 to 60 cm. in length and were cut 
at 15 micra. In addition there were prepared one transverse 
and one frontal series through the entire head of carp of 3 em. 
in length. The method followed in this case is as follows; the 
fish are placed in Miiller’s fluid, changed every second day, for a 
month, and then decalcified for another month in Flemming’s 
