1712 JOTTINGS FROM THE UNIVERSITY BIOLOGICAL LABORATORY, 
terior abdominal appendages, which in the female crab are well 
developed and serve for the attachment of the eggs, were found to 
be wanting. The specimens in fact were males ; but males in 
which such a remarkable modification had taken place that they 
presented externally all the characters of the females, and in which, 
moreover, the external parts specially characteristic of the male 
— the modified appendages of the first and second segments of the 
abdomen — were quite rudimentary. 
12. On A METHOD OF PREPARING BLASTODERMS OP THE FOWL. 
The following method I have found of great value in expediting 
the processof removing and preparing the blastoderms of early stages 
(up to the third day), and also in diminishing the risk of injury. 
The fixing fiuid 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 blastoderm. 
An ordinary conical measuring glass of a capacity of 100 c.c., 
with the edge turned out and with a large ‘ lip,’ is placed in a flat 
dish and is filled to the very brim with nitric acid. The egg shell 
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 invests the yolk is peeled off as one 
might peel off the outermost coat of an onion, leaving the yolk 
and blastoderm with the investing vitelline membrane quite entire 
and perfectly clean in the glass — the entire white having in this 
way spontaneously thrown itself off. The whole process takes 
only two or three seconds. If, as occasionally happens owing to 
* ‘ Methods ia Microscopical Anatomy and Embryology,’ p. 167. 
