CHAPTER I 



THE PROBLEM OF MORPHOLOGIC VARL\TION 

 OF BACTERIA 



Bacteriology has developed more as an applied science than as 

 a theoretical one, and the fundamental biological problems of the 

 bacteria have been neglected. There are many reasons for this, but 

 perhaps one of the most important has been the blind acceptance 

 by the majority of bacteriologists of the Cohn-Koch dogma of the 

 constancy of cell forms and the immutability of bacterial species, 

 which has discouraged all investigation of problems of morphology, 

 inheritance, and variation in bacteria for a good many years. The 

 progress of science is measured not so much by the wealth of fact 

 established as by the veins of unsolved problems uncovered, and the 

 moment a field of knowledge comes to be considered complete, at that 

 moment this branch of science is dead. It is therefore a healthy 

 sign that within recent years, through the activities of a small but 

 persistent group of modern pleomorphists, bacteriology is definitely 

 breaking away from the Cohn-Koch tradition and is seriously re- 

 opening for discussion and investigation the old problem of morpho- 

 logic variation in bacteria. 



But this movement has within it that danger inherent in all revo- 

 lutionary movements, the tendency to go too far in the opposite 

 direction. It does not necessarily follow that because Koch was 

 wrong Naegeli was right; and yet in the writings of at least some 

 of these new pleomorphists, their protests to the contrary not- 

 withstanding, there is clearly evident a tendency to return to the 

 old idea that any bacterium may transmute to the form of any other. 

 Von Niessen, referring to Xohnis' work, exclaims, "Im Prinzip 

 Naegeli redivivus, Bestdtigung deiner Befunde, vollig unabhdngig 

 und rein wissenschajtlich, und — was wird die jiihrende Kochshe 

 Schule dazu sagen?" and indeed the dominant school of bacterio- 

 logists has so far had very little to say. A hypothesis endlessly 

 repeated without criticism becomes a dogma, and it is high time there- 



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