BY WILLIAM A. HASWELL. 
1713 
some of the fluid having been splashed out of the glass in pouring 
in the egg, the white does not begin to run over the edge, a little 
of it should be pushed over the lip and left to draw the rest after 
it in the manner described. 
The entire yolk with the blastoderm should be left for half-an- 
hour in the glass with the nitric acid : it may then, part of the 
acid having been poured off, be turned into a large dish full of 
water which has to be changed several times. After the yolk has 
been for a few minutes in the water the blastoderm has to be cut 
out with scissors, when it will readily peel off from the underlying 
yolk, and the vitelline membrane readily comes away. The 
blastoderm is then to be left for half-an-hour in water, which should 
be renewed, and then transferred to weak alcohol (60%), in whicli 
it should remain for twelve hours ; it should then be placed for 
two days in 90% alcohol, and then stained by immersion for three 
or four hours in Ehrlich’s hsematoxylin (crystallised hsematoxylin 
2 grms., water 100 c.c., glycerine 100 c.c., acetic acid 10 c.c.), 
followed for a few minutes by acidulated alcohol (97 c.c. 70% alcohol, 
3 c.c. hydrochloric acid), and that in turn for half-an-hour or more by 
alcohol diluted to 70% by the addition of ordinary tap-water or 
water artificially rendered slightly alkaline. The specimen will 
then be ready, after pas.sing through 90% and absolute alcohol, for 
mounting as a whole. For sections it is better to omit tlie 
acidulated alcohol, and to allow the specimen three days further 
hardening in 90% and absolute alcohol. 
The important point here is, of course, the ease and rapidity 
with which the white is got rid of, so that a large number of 
blastoderms may be prepared in a comparatively short time. But 
the mode of subsequent treatment described above, which is 
applicable to blastoderms j)iepared in other ways, gives results, 
particularly for whole blastoderms, such as are not obtained by 
any other of the many methods I have tried. 
13. Note on Uholoi-iius testackus. 
In my “ Studies on the Elasinobranch Skeleton,” published in 
the “ Proceedings” of this Society (Vol. IX.) there is a very brief 
