CHAPTER VII 

 THE DISSOCIATIVE ASPECTS OF BACTERIAL BEHAVIOR 



PHILIP HADLEY 

 University of Michigan 



INTRODUCTION 



Two of the most remarkable circumstances relating to the development of bac- 

 teriology during the past half-century are: first, that bacteriologists have been so long 

 content to conduct their experiments and to formulate their views in terms of the old 

 monomorphic hypothesis regarding the nature of bacteria and of bacterial reproduc- 

 tion; second, that they have been so active in evolving inadequate schemes for class- 

 ification before they knew exactly what it was they had to classify. Looking back on 

 the road over which we have traveled, it is impossible to estimate the loss sustained 

 by bacteriology, especially in latter years, through the repressive and misguiding in- 

 fluence of the strict monomorphic conceptions, or to appreciate the often serious bio- 

 logical blunders that are to be laid at its door. In times of festival and jubilee we are 

 accustomed to congratulate ourselves on the significant conquests of modern bacteri- 

 ological science; and they have, it is true, been considerable. But they should have 

 been greater; and they would have been far greater today if the science, a half- 

 century ago, had not become impaled on a false biological conception which has never 

 ceased to influence unfavorably both bacteriological thought and practice. And 

 which, it may be added, even today represents a malicious dogma, accepted by tradi- 

 tion, if not actually embraced by perhaps the majority of bacteriologists. 



The doctrine of monomorphism has descended to us from the early conceptions of 

 the nature of bacteria maintained by Cohn, Koch, and others of the early school. 

 Under its influence, in the earliest and most plastic days of the science, there were set 

 up strict notions of "normal" bacterial cell types, "normal" colony forms, and "nor- 

 mal" cultures. Whatever departed from the expected normality was at once relegated 

 to the field of contaminations; or to the weird category of "involution forms," "de- 

 generation forms," or pathological elements possessing neither viability, interest, nor 

 significance. This monomorphic conception found its natural and fundamental sup- 

 port in the assumed mode of reproduction characteristic of the fission-fungi. The dic- 

 tum was then laid down that "the mode of reproduction of bacteria is by simple 

 fission" — a view which has descended through two generations of bacteriologists and 

 through numerous generations of textbooks, even to the year 1927. 



Although some early opposition to these views arose, it was probably unfortunate for 

 the beginnings of the science that the first attempts toward modification were made by such 

 extremists as Niigeli and his associates in the Munich group. The extreme plurimorphism 

 which they so eagerly championed through years of bitter controversy was too radical to be 

 accepted graciously as an antidote to strict monomorphism. Kor this reason Niigeli gained 

 few permanent supporters; and, with the hnal collapse of his views, all views, even those 



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