PHILIP HADLEY 85 



espousing a more temperate plurimorphism suffered. The interpretations of the Berlin school 

 triumphed — and to such an extent as to become later the dogma of "normal" colony and 

 culture types that has endured, with hardly a respite, even to the present day. 



There did arise, however, at a later date some slight reaction to the monomorphic trend 

 of the science. In the later eighties Gruber and his pupils were demonstrating examples of 

 common and often curiously persistent variability in bacterial cultures. These observations 

 were at variance to the demands of the Berlin group, although the instances concerned also 

 fell far short of conforming to the extreme variability earlier pictured by Niigeli.' The same 

 was true of the depictions of variability presented in the splendid series of contributions of 

 Eisenberg.^ "Pathological variants," "involution forms," and "degeneration forms" were 

 for a long time quite adequate to dispose of all such insignificant, though still somewhat 

 bothersome, departures from the "normal" type. In 1906 and 1907, however, the variation- 

 ists were fortunate enough to secure a more logical and trustworthy outlet for their explana- 

 tions of "abnormal" forms of cells or cultures. This was found in the observations of Neisser' 

 and of Massini-* on B. coli mutahile, whose pictures of variation they believed involved the 

 phenomenon of mutation. In this way the De Vriesian term, together with many of its con- 

 notations, was first introduced into bacteriology. This event was the starting-point for nu- 

 merous observations and studies on mutating bacterial forms; and the discovery of bacterial 

 "mutants" has continued without appreciable interruption up to the present day. Seldom, 

 however, has the De Vriesian term been used advisedly. Its employment has merely provided 

 a dignified and logical escape from the increasingly unacceptable "involution" hypothesis, 

 as also from the necessity of offering any other more valid explanation of the phenomena 

 concerned. The general result has been to bring into bacteriology many of the terms em- 

 p'oyed in genetics — "plain variations," "impressed variations," "hereditary variations," 

 ''clones," "biotypes," and "pure lines." But the conceptions apparently supported by the 

 somewhat lavish use of these terms have usually lacked concreteness; and in few instances 

 have the appellations been either appropriate or logical. For the most part, notions of bac- 

 terial heredity among bacteriologists have been marked by extreme haziness and uncer- 

 tainty. 



Beginning about 1907, however, there began to arise among the variationists two groups: 

 first, the larger group of strict variationists who saw in their culture modifications merely a 

 transient, but sometimes permanent (hereditary), departure from the otherwise monomor- 

 phic type; second, the cyclical variationists, hardly numerous enough to term a group, and 

 represented by such workers as Fiihrmann,' who believed that they could detect a certain 

 order and direction in the culture modifications. Later supporters in this group have been 

 rare — six only who, since the year 1907, have combatted to the best of their ability the false 

 but always overwhelming views of bacterial type-stability. These investigators merit nam- 

 ing at this point in our story; they are I'lihrmann, Hort, Almquist, Lohnis, Enderlein, and 

 Mellon. To these workers particularly may be given the credit for directing the current of 

 bacteriological thought into new channels. 



'v. Nageli, C: Untcrsuchungcn iiber die nielere Filze iind ihren Beziehiing zu den Infektions- 

 krankheiten itnd der Gcsiindhcitspjlcge. 1877. 



^ See Bibliography in monograph on microbic dissociation by Hadlcy, Philip: J. Infect. Dis., 40, 

 I. 1927. 



i Neisser, M.: Centralbl.f. BakterioL, Abt. I, Orig., 38, 98. 1906. 



'•Massini, R.: Arch.f. Ilyg., 61, 250. 1907. 



sFiihrmann, F.: Verli. d..ges. deiitsch. Natiirf. u. Arize, p. 278. 1906. 



