ADDENDA. 
THE CHEMISTRY OF ANIMAL PARASITES. 
Some parasites cause harm mechanically and pre- 
sumably in no other way. In most of them there is 
more or less evidence of the formation of a poison- 
ous substance. Little, is as yet, known of the chem- 
istry of animal parasites or their excretions. It is 
known that the cells, at least in part, differ in 
chemical composition from the cells of the higher 
animal organisms. Chitin is one substance that con- 
stitutes a large part of the outer coverings of en- 
cysted parasites as well as the outer portion of many 
of the worms. 
A chemical study of the bodies of the strongiles 
show their bodies to yield fats, fatty acids consisting 
principally of butyric acid, soaps, mucin, albumoses, 
purin bases and creatin. A ptomain, a crystalizable 
alkaloid, an amino acid and an amorphus substance 
containing non-protein nitrogen and phosphorus which 
gives precipitating reactions for an alkaloid. The cuti- 
cle ccutains a protein like substance which has no rela- 
tion to chitin. An alcoholic extract of these parasites 
possesses strong hemolytic properties. The soaps, 
fatty acids, crystalizable alkaloids and ptomains are 
active in this hemolytic process. The parasites secrete 
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