MORPHOLOGIC VARIATION OF BACTERIA 5 



variations in serologic or cultural characters rather than morphology, 

 but the origin of the former is traced to the latter in every case; 

 some of his work has had to deal with pathogenic fungi rather than 

 bacteria. Again the work is too voluminous to be readily summarized 

 in a few words. But the main idea seems to be, as in the case of 

 Lohnis, that bacteria go through a more or less complex life cycle 

 in which various types, rods, spheres, branching forms, etc., appear 

 in sequence; further, that any one of these types may be stabilized, 

 i.e., continuously reproduce itself, without going through the rest of 

 the cycle. The origin of these stabilized types is sought in sexual 

 reproduction, which is found particularly in the case of the colon 

 bacillus in the formation of large globular swellings, previously de- 

 scribed and illustrated by Scales, at the point of fusion of two rod 

 forms, and designated by Mellon as zygospores, though conidia and 

 even endospores are thought to involve at least a process of autogamy. 

 Mellon believes that the name applied to these structures is relatively 

 unimportant as long as the essential factors of conjugation and nu- 

 clear reorganization are recognized. He also describes the separation 

 of variants from cultures by filtration which differ markedly from the 

 parent strain, especially in virulence, and implies, as have the pre- 

 ceding authors, that these variants have been derived from minute, 

 perhaps ultramicroscopic, conidia. 



The latest, and perhaps most remarkable contribution to this 

 new pleomorphism is the work of Enderlein. He unfortunately has 

 found it necessary to coin a vocabulary of nearly two hundred new 

 words to express his ideas, which proves a serious obstacle to the 

 reading of his work. Once this vocabulary is mastered, however, one 

 finds that the hypothesis is presented with a clearness and coherence 

 that is annoyingly lacking in the papers previously reviewed. I say 

 hypothesis, for one gains the impression that the ideas expressed are 

 pure theory having only the most slender basis in actual observation. 

 Only slight details of technique and brief descriptions of actual ob- 

 servation are given. The drawings, made with extremely high mag- 

 nifications, are not convincing. His description of the centrosome 

 with dimensions of 0.01 pi, which, as is well known, is quite below 

 the limits of resolution of the microscope, seriously impairs one's 

 faith in the accuracy of his other observations. This impression 



