1890.] : Microscopy. 865 
Sale vary considerably in consistency, according to the species, 
and different methods are consequently required. The denser forms, 
such as S. zonaria, shou e placed in a mixture of roo c.c. fresh 
water and ro c.c. concentrated acetic acid, where they should remain 
for fifteen minutes. They should then be washed in fresh water for 
ten minutes, and pass gradually into alcohol. Less dense forms, such 
as S. democratica mucronata, may be fixed in chrom-acetic mixture, No. 
1, and then passed directly into fresh alcohol; while the soft forms, 
such as S. pinnata and maxima, should be placed in chrom-osmic mix- 
ture for 15 to 6o minutes, then washed in fresh water, and transferred 
to weak alcohol. 
Fishes.— Amphioxus will die with the buccal cirrhi distended in sea- 
water alcoholized to ro per cent. They should then be transferred to 
50 per cent. alcohol, and gradually to 7o per cent. 
Other forms may be preserved in alcohol (70 per cent.), taking care 
to make a ventral incision, and also to inject the alcohol and renew it 
frequently at first. If it is wished to preserve some of the larger 
Selachians for some months in order to prepare at leisure the skeleton, 
the intestines should be removed, and the animals placed in a 1o per 
cent. solution of salt. 
Elasmobranch embryos may be fixed in corrosive sublimate, leaving 
them in the solution for 5 to 15 minutes, afterwards washing well 
in iodized alcohol. Embryos of Torpedo with the yolk were preserved 
by immersing them in a mixture of equal parts of ı per cent. chromic 
acid and corrosive sublimate for fifteen minutes, and then transferring 
to alcohol. 
Transparent fish eggs may be preserved for the purpose of demon- 
stration by subjecting them for a few minutes to the action of. the 
alcohol and hydrochloric acid mixture, and then transferring them to 
. pure alcohol.—PLAYFAIR M’Murricu. 
