division, c. fluid

The fluid part of a c. as distinguished from its solid or semisolid part. It is supposed to fill the vacuoles in c's. c. fusion. The union of two or more c's in such a manner that the adjacent c. walls are absorbed and the separate c. bodies united into one. c. genesis. The development or formation of c's. Two forms of c. genesis are distinguished: 1, asexual c. development, comprising all cases in which a parent c. without previous conjugation with another c. develops into new c's; 2, c. union, c. conjugation, sexual c. development, in which two c's, which are sometimes similar but are usually di imilar in size, shape, or both, coalesce and form a single c. which then develops into new c's. C. genesis of either form may take place in two principal ways: 1, by c. division and, 2, by internal c. formation. The former includes, as a special variety, c. budding or gemmation, which comprises many of the proce es of spore formation. Internal c. formation (g. v.), which is a still more specialized variety of c. division, comprises free c. formation and rejuvenescence, c. histology. The science which treats of the minute structure of c's in contradistinction to histology proper, which deals rather with the structure of the ti ues, c. layer. A layer or stratum of c's, such as a simple epithelium or part of a stratified epithelium, c. life.