R I. PRODUCTION 9I 



to enable them to crawl as a unit. There is much more apparent variation in 

 the form oi' such fusion cells in myxobacteria than in eubacteria, and they 

 are rather less frequent. 



In Sphcerotilus natans, a clilamydobacterium, the form of the fusion cells 

 and their nuclei is similar to that of smooth eubacteria, but their behaviour 

 is not known. 



Sexual vegetative reproduction has not been reported in spore-bearing 

 bacilli, but the matter has been so little investigated that it would be rash to 

 suggest that it does not occur in exceptional cases. 



In M. tuberculosis Lindegren and Mellon (1933) have described the pro- 

 duction of nucleated coccal gametes, which conjugated sexually to produce 

 larger coccal bodies. The latter fragmented into tetrads, from which the 

 customary bacilli arose once more. As the unit cell of which a mycobacterium 

 is composed is a small coccal body, this process does not differ in its essentials 

 from sexual, vegetative reproduction in BacteriacecF. Many similar observations 

 upon mycobacteria are less clear in their inferences because the workers 

 ■concerned were apparently unaware of the processes which correspond to 

 vegetative fission in bacteria of this morphology. 



E: FISSION IN MYCOBACTERIA AND CO RYNEBAC T E RI A 



(7, 10, 14, 18, 19, 27, 28) 



Mycobacteria and corynebacteria possess a morphology which differs 

 :strikingly from that of other rod-shaped bacteria. Bacilli of these genera 

 may consist of a single, spherical or oval cell, or of a dozen or more such cells. 

 Often the terminal cells are much larger than the others, and the contents 

 ■of such enlarged, terminal cells constitute the metachromatic granules oi 

 C. dipJitlicria\ In the case of M. tuberculosis the cells are more usually similar 

 in size, or approximately so, and the beaded appearance of the bacillus in a 

 preparation stained by Ziehl-Ncclscn's method is due to shrinkage of the 

 ^cell contents. 



