MORPHISM

MORPHISM, or uniformity: 1) The phenomenon of homogeneity of external form in all individuals belonging to the same species, observed in most animals. It is contrasted with polymorphism (see), or multiformity, when a species consists of several categories of individuals differing from each other both in external appearance and in functions. In morphic animals, even significant external sexual differences are absent. The term M. is applied not only to solitary animals but also to colonial animals, for example, one speaks of morphic and polymorphic colonies of bryozoans. 2) In microbiology, M. is the doctrine of the presence in each bacterial species of a constant characteristic form specific only to this species; M. is contrasted with pleomorphism, i.e., the outdated doctrine that all microbial species are connected by mutual transitions, assuming one form or another depending on the conditions of existence: cocci can transform into bacilli, bacilli into spiral forms and vice versa. A convinced defender of M. was Cohn, whereas pleomorphism was defended by Nägeli with his school and a number of other prominent scientists.