Morphologic variation and the rate of growth of bacteria, by Arthur T. Henrici ...

Abstract

that the work is a philosophical one rather than the result of labora- tory observation is supported by the fact that the author is a zoolo- gist who has made no other contribution to bacteriology.Enderlein considers the cytology, life cycles, and taxonomy of bacteria.The basis of his cytology is the primitive nucleus or ''mych."This with its accompanying protoplasm forms the "mychit," which is the building stone of bacterial cells.It may exist by itself as in the micrococci, or may combine with others in various multi- ples to form "pliomychits," the cells of larger or more complex bac- teria.Asexual reproduction is accomplished through equational cell division, "monogony," in the case of a mychit; "isomorphous ar- throgony" in the case of more complex cells; or by unequational cell division, "heteromorphous arthrogony," which can occur only with pliomychits.The latter may give rise to a number of different repro- ductive bodies: Gonidia, which contain a single mych; the "cystit," a gonidium with a compound nucleus ("polydynamen mych") ; the ''cystoid," an unusually large gonidium with much reserve foodstuff; structures behaving like embryos in that they grow at the expense of a neighboring or enclosing mother cell; and structures like the oidia of higher fungi formed by the multiple fragmentation of a cell.Sexual reproduction is accomplished by the development of gameto- cytes from gonidia.These undergo a reduction division of the mych, the haploid mychit resulting being called a "gonit."The latter may develop into a male cell ("spermit") or a female cell ("oit").The former, in the case of the cholera vibrio, is smaller, curved, and actively motile by means of a polar flagellum ; the latter is larger, globular, and but sluggishly motile.These unite, followed by a fusion of their respective nuclei, giving rise again to the diploid phase.Enderlein also confirms Lohnis' observation of the symplasm.The life cycle of a bacterium, according to Enderlein, consists of two simultaneous, parallel, and co-ordinated processes, a multiplicative development through simple cell division, and a progressive develop- ment {'^fortschreitenden Entwicklung'^) , very slow and characterized by morphologic variation.The former is "auxanogeny," the latter "probseogeny."As the ontogeny of an individual repeats the phylogeny of the race, so the life cycle of a bacterium repeats the evo- lution of the species; and as a multicellular organism cannot avoid