MORPHOLOGIC VARIATION OF BACTERIA 9 



bacteria may bud, branch, form gonidia, and even structures com- 

 parable with asci. The latter characteristic implies a complicated 

 life cycle sexual in nature. . . In any event, it is clear, and now beyond 

 dispute, that Koch's law of morphologic type specificity cannot longer 

 be regarded in the absolute sense which has characterized it in the 

 past. Bacteria do change their morphologic type and within very 

 wide limits; and with this change may go at times important physio- 

 logical modifications" (1927, p. 107). 



Much can and will be said in criticism of both the work and 

 the hypotheses of these men, but this criticism should not in any 

 way minimize the real value of the service which they have rendered 

 to bacteriology in reopening for discussion and investigation this 

 fundamental problem. Confronted with the cold skepticism towards 

 questions of morphologic variation in bacteria common to bacteri- 

 ologists a decade ago, it required real courage to publish papers of the 

 type here reviewed. And while these papers have probably 

 not convinced more than a very few that bacteria exhibit complex 

 fungoid life cycles, they have demonstrated beyond question of a 

 doubt that bacteria do regularly show pronounced morphologic vari- 

 ations, the nature and significance of which must be determined 

 before we can make any real progress towards understanding the 

 fundamental biological problems of the group. 



One can no longer satisfactorily answer their arguments by the 

 old formula that they are dealing with irnpure cultures; for while un- 

 doubtedly in isolated cases conclusions have been drawn from obser- 

 vations of contaminated cultures, this is by no means general, and 

 anyone who will patiently study with the microscope his own cul- 

 tures which he knows to be pure can quickly confirm the general 

 observation that rod forms may appear in cultures of cocci, spherical 

 forms in cultures of bacilli, lateral buds and branches, and internal 

 globular bodies in both. In undertaking a critical analysis of this 

 work, then, one cannot find iault so much with the actual data as 

 with the logic followed in erecting the hypothesis. 



But the data are not beyond criticism. Throughout these papers 

 one is impressed with the meagerness and haphazard character 

 of the observations as compared with the widespread importance 

 of the conclusions. The small amount of data submitted may per- 



