110 METHODS OF COLLECTING AND PEESEEVING 
TUNICATA. 
The minute tailed Ascidians, known as Appendiculariw, sometimes 
occur in abundance at the surface of the sea. Signor Lo Bianco 
recommends that they be killed by leaving them for five minutes 
in a mixture of chrom-osmic acid (see " Ctenophora ") ; they are 
then washed and graded (see p. 98) in alcohol. 
The pelagic Tunicata (Pyrosoma, Salpa, Doliolum) are killed and 
fixed with osmic acid, washed in fresh -water, and transferred to 
strong spirit or 8 per cent, formalin. 
Simple and compound Ascidians should be narcotized by placing 
them for some hours in chloralized sea-water containing hydrate of 
chloral 1 in 1,000. They may then be put into strong spirit or 8 per 
cent, formalin, which should be changed after twenty-four hours, 
because Ascidians contain much water. 
Mr. A. B. Lee* strongly recommends for Compound Ascidians a 
process employed by Professor Van Beneden. The corm is placed in 
clean sea -water for a few hours. When the zooids are extended, the 
corm is seized with the fingers and dropped into glacial acetic acid, 
and left there for from two to six minutes. It is then removed with 
the fingers, and washed well in 50 per cent, alcohol, and graded into 
successively stronger alcohols up to 70 per cent. This method avoids 
the use of steel, and will not injure the fingers if they are washed 
at once. 
Mollusca. 
Lamellibranchs and Heteropods should be narcotized in alcoholized 
sea -water. To avoid the closure of the valves of Lamellibranchs 
on immersion in 70 per cent, alcohol, little plugs of wood should be 
placed between the margins of the valves. The same result may 
be effected in the case of Prosobranchs by tying the internal edge of 
the operculum to the shell. 
Of the Opisthobranchs the iEolids may be best preserved by 
pouring over them • concentrated acetic acid in volume equal to 
or double that of the sea-water containing them. Dorids should 
lit st, be narcotized by gradually adding 70 per cent, alcohol to their 
* A. V). Lee, " Microtomist's Vade Mecum," 5th edit., 1900, p. 460. 
