Structure and Function in the Nematodes: Internal Pressure and Cuticular Structure in Ascaris

ABSTRACT No one who has made even a casual study of the Nematoda can fail to have been struck by the extraordinary similarity in form and organization between the very large number of species, genera, orders and families which constitute this class of the very diversiform phylum Aschelminthes. Though there are species which show some variation from the normal ‘nematode facies’, they are few in number and merely seem to emphasize still further the great uniformity of the group as a whole. The characteristic features of the nematodes are present in fresh-water, marine and parasitic forms; they are largely independent of size, of diet and of stage of development.