Parasites which inhabit the human alimentary canal are usually described as entozoa or intestinal worms. There are about 20 different known species of the entozoa, all of which infest the alimentary canal of vertebrate animals or man. Entozoa of the order of Cestoda are commonly known as tapeworms, and of this particular worm about 10 different varieties have been observed and studied. They inhabit either the intestines of some vertebrate animal or man, but it is the parasite infesting the alimentary canal of man with which the physician is chiefly concerned.
DESCRIPTION AND VARIETIES.
Three species of tapeworm are of special interest to the medical practitioner and all are usually found in the upper third of the small intestines.
1. Tænia Solium (Pork Tapeworm).
—This is an armed parasite, the head of which is provided with a circle of minute hooklets for the better attachment of the worm to the