Ramsey, Optic Lobes of Amblyopsts. 45 
Methods. 
I. The most successful method used is as follows. The 
brain is fixed in Fou ’s mixture of picric, osmic, platinic and 
acetic acids for from three to four days. It is then put into 
pyroligneous acid for two days. It is next washed in wood 
alcohol until the alcohol is no longer tinged yellow. After be- 
ing dehydrated in the usual way, it is saturated in chloroform 
and imbedded in paraffin, after which it is sectioned and 
mounted in balsam. ‘The acids serve as stains as well as fixing 
agents, and differentiate the various structures excellently. 
2. For other phases of the work, the following was found 
good: . 
Fish were killed~by cutting the spinal cord just back of the 
medulla. The large blood vessels are cut while the heart 
still beats, that as much blood as possible may be drained away 
from the brain. The blood corpuscles give a very deceptive 
appearance when stained in the vessels penetrating the brain. 
Before placing the brain in alcohol, cut away as much of 
the head as possible without injuring the brain. This al- 
lows the alcohol to penetrate uniformly and prevents the brain 
from becoming colored, as.it does when the surrounding tissue 
is not removed. The head then is placed in 35, 50, 70, 
85, and 95 per cent. alcohols for twelve to sixteen hours in each 
grade. The brain is easily removed from the head and placed 
in absolute alcohol for four or five hours. It should zot¢ show 
any shriveled appearance, as it will if fixed in a high grade of 
alcohol at once. It is now put in choloform until it sinks, when 
it is put in the paraffin bath, and imbedded. Sections are cut with 
a sliding microtome, the sections alternating 15 and 20 yp, since 
some points are more easily made out in the 15 y sections, while 
others are best found in those 20 » thick. They are fixed by 
the distilled water method. The paraffin is removed with xylol 
and the slide washed with 95 per cent. alcohol for a minute or 
two to remove the xylol. The slide is placed in the stain, which 
is prepared as follows: Dissolve 0.3 g. dry methelyn-blue in 250 
cc. distilled water. Add to thiso.t g. or 0.2 g. of any good un- 
