Microscopy. 857 
MICROSCOPY. 
Tue Eees or Ampurera.—I have found hypochlorite of sodium 
an excellent solvent for the gelatinous envelope of the amphibian 
egg. I obtained a ten per cent. solution, and diluted it with five 
or six times its volume of water. The eggs are first hardened by 
heating, or by immersion in some preservative fluid ; then placed in 
the Labarraque solution until the gelatinous envelopes are so far 
dissolved that the eggs may be easily shaken free. They are then 
washed and preserved in alcohol. This method works perfectly 
with the eggs of Necturus, and has given equally good results with 
the eggs of the frog. The time required for dissolving the envelope 
in the case of Necturus is about five minutes. Care should of course 
be taken not to leave the eggs exposed to the solvent longer than is 
necessary in order to destroy the envelope. 
EXPERIMENTS wrra Currin Sotvents By T. H. Moraan2— 
The first experiments were made upon the eggs of the common 
cockroach, and the selection turned out to be a most for- 
tunate one. A great many eggs are laid at one time, the whole 
number being surrounded by a stiff chitinous coat, forming the 
so-called raft 
The solvents used were the hypochlorites of sodium and potassium, 
recommended by Dr. Looss in 1885 
The most successful experiments on the cockroach’s eggs were as 
follows: 
„1. The rafts were placed, in a fresh condition, in a weak solution 
of eau de Labarraque (commercial fluid diluted with five or six 
times its volume of water), and left until the chitinous envelope 
e soft and transparent. The time varies; if slightly warmed 
the time is less, for the warm solution perhaps thirty minutes to 
one hour; but one must go more by the appearance of the chitin 
than by any definite time. If the embryos are far advanced they 
may now be removed from the envelope one by one ; if still young, 
they had better be hardened and cut altogether. In both cases the 
eggs or embryos were next washed for a fow minutes in water, and 
then transferred for an hour to picro-sulphuric acid, then as usual 
they are passed through the grades of alcohol, 70 per cent., 80 per 
cent., 95 per cent. 
1 Edited by C. O. Whitman, Director of the Lake Laboratory, Mil- 
waukee. 
Vo Studies from the Biological Laboratory, Johns Hopkins University, 
Ol. iv., No. 4, p. 217, 1888. 
