MICROSCOPY. 
On a method of preparing blastoderms of the Fowl.— 
Hasnell {Proc. Linn. Socy. New South Wales, i88g) has found the 
following method of great value in expediting the process of removing 
and preparing the blastoderms of early stages (up to the third day), 
and also in diminishing the risk of injury. The fixing fluid used is 
ten per cent, nitric acid, as employed by Whitman and others. The 
novel point in the method is the mode of getting rid of the entire 
white without any trouble, and without risk of damaging the blas- 
An ordinary r^/w'^a/ measuring glass of a capacity of loo c.c, with 
the edge turned out with a large " lip," is placed in a flat dish, 
and is filled to the very brim with nitric acid. The eggshell is then 
broken, and the entire contents poured into the glass in exactly the 
method adopted in the kitchen, except that the egg is held when being 
opened close over the glass so that there may be as little disturbance 
as possible. The glass being brim full, when the contents of the egg 
are added to it a quantity of the fluid runs over the sides ; with this 
there begins to run some of the external, more fluid, part of the 
white ; as this runs over, it by its weight gently draws the firmer part 
of the white with it, and finally the firm layer' which immediately in- 
vests the yolk is peeled oft" as one might peel off the outermost coat 
of an onion, leaving the yolk and Ma^todeini with tlie investing 
vitelline membrane quite entire and perfectly clean in the glass — the 
entire white having in this wav spontaneously thrown itself ofi". The 
whole process takes only two or three seconds. If, as occasion- 
ally happens, owing to some of the fluid having been splashed out of 
the glass in pouring in the Qgg, the white does not begin to run over 
the edge, a little of it should be pushed over the lij), and left to draw 
the rest after it in the manner described. 
