(158°-176° F.). Allow this mixture to act for 10 to 20 minutes. 
Subsequently these worms should be washed and then put in a tinc¬ 
ture of iodin to remove the excess of corrosive sublimate. For col¬ 
lecting specimens in the field or wherever there are no laboratory 
facilities, a weak formalin solution, one to two percent, is fairly 
satisfactory. 
Nematodes may be examined in physiologic saline while yet 
alive or cleared for study by transfer from 70 percent alcohol to the 
same strength of alcohol containing 5 to 10 percent glycerin. This 
mixture and the contained worms may then be placed in an incubator 
or paraffine oven and kept there until the evaporation of the alcohol 
leaves the specimens in glycerin. By this time the specimen is usually 
quite clear and the transfer to glycerin is sufficiently slow to prevent 
the distortion of the specimens by osmosis. The worms may then be 
permanently mounted in glycerin or glycerin jelly. Some nematodes, 
especially small ones, may be transferred to glycerin jelly directly 
from 70 percent alcohol without sufficient distortion to make an ordi¬ 
nary identification at all difficult, but large worms are usually much 
distorted by such a transfer. Another clearing agent consists of 20 
parts of absolute alcohol and 80 parts of carbolic acid. Nematodes 
are rarely stained for examination by most workers, as they are not 
amenable to most stains, but gentian violet is fairly penetrating and 
may be used to bring out many interesting details of structure. 
Haematoxylin is also used at times and gives a good picture. Oc¬ 
casionally nematodes are dehydrated, cleared and mounted in balsam, 
but this often makes them too transparent for some purposes and 
simpler and quicker methods are usually quite as satisfactory or more 
satisfactory. 
Tapeworms and flukes are usually stained, dehydrated, cleared 
and mounted in balsam for study and identification. Tapeworm scolices 
or heads may be mounted in glycerin, glycerin jelly or similar media 
for the examination of the hooks, and gravid segments are sometimes 
similarly mounted for the purpose of examining the eggs. 
Probably there is no field in which the veterinarian can find 
more new scientific facts with more ease than in the field of parasitol¬ 
ogy. A number of interesting parasites of the domesticated animals 
10 
