
760 The American Naturalsst. [August, 
be freed in the following manner: With a pair of sharp scissors each 
egg must be cut out from the general jelly-mass, retaining as small an 
amount of surrounding jelly as possible. It is then put into an alco- 
holic solution of picric acid for an hour or longer (one to twelve). 
The solution is prepared by saturating 35 per cent. alcohol with picric 
acid, and adding the same amount of sulphuric as in Kleinenberg’s 
solution. The solution is not diluted, but used saturated with picric 
acid. The eggs are then washed for several hours in 35 per cent. alco- 
hol, several hours in 50 per cent. alcohol, and placed in 70 per cent. 
for several days, changing the alcohol once or twice if necessary. 
About the second day the inner membrane begins to swell, due to a 
slow osmotic action, I think, as the membrane is stretched by tension 
from within. On the third or fourth day the swollen membrane may be 
pierced by a sharp needle, and the egg taken out, which is then placed 
permanently in 80 per cent. alcohol. The method is exceedingly 
simple, and consists largely in waiting a few days for the osmotic 
action to take place. Such eggs, if properly prepared, are in excel- 
lent histological condition. This simple method has proved so suc- 
cessful that I have not further experimented with it. It is possible 
that it may be improved by varying the strength of alcohol used, but I 
have not seen the need of looking further. The membrane does not 
swell in stronger alcohol than 70 per cent., and weaker would macerate 
the eggs. 
Certain precautions are necessary in imbedding the eggs to prevent 
brittleness. This is obviated by soaking the eggs before imbedding, 
for several hours, in a solution of turpentine saturated with paraffine, 
and kept in a warm place,—not so hot as the water-bath (50° C.). 
Heat causes the egg to become brittle. This is obviated by the above 
process of soaking, so that the egg need not remain so long as an 
hour in the melted paraffine of the water-bath. In the younger stages 
there is no need for very thin sections, but sections ro x thick are suf- 
ficent for all purposes. If the sections are cut too thin the yolk tends 
to break up and crumble.—T. H. Morcan, May rst, 18921. 




