A considerable part of the alimentary canal is said to be derived from the ectoderm in the buds of both Cephalodiscus and Rhabdopleura.
It is probable that the parasite is then transferred to the alimentary canal of man by means of drinking-water, and thence makes its way to the subcutaneous connective tissue.
The adult worm, which is of extremely minute size, the male being only Fi l sth and the female s of an inch in length inhabits the alimentary canal of man and many other carnivorous mammalia; the young bore their way into the tissues and become encysted in the muscles - within the muscle-bundles according to Leuckart, but in the connective tissue between them according to Chatin and others.
Insects, indeed, are largely concerned in disseminating Fungi, either on their bodies or via the alimentary canal.
The Oligochaeta are the only Chaetopods in which undoubted nephridia may possess a relationship with the alimentary canal.