102 THE CYTOLOGY AND LIFE-HISTORY OF BACTERIA 



claimed by Schaudinn (1902-03), in die earliest cytological study ot sporulation, 

 that the fusion is preceded by a partial cell division. This point is not clearly 

 established by the available evidence. Klieneberger-Nobel (1945) claims 

 that cell-division occurs after fusion, but this must be regarded as the production 

 of a diploid, vegetative generation, such as occurs, more elaborately, in 

 streptomyces. It is not a reduction division, as this occurs at a later stage. 



The nuclear material derived from the four cells of the rough bacillus, 

 or from the two nuclear units of the smooth cell, forms a longitudinal, rod- 

 shaped fusion nucleus (Chapter IV). In both cases the unit which forms the 

 zygote and produces the spore is the bacillus, whether unicellular or otherwise. 

 This is not true of the formation ot the resting nucleus in rough eubacteria, 

 or in M. tuberculosis, in which the unit is the cell (Chapter IV and Sections 

 D, E, F below). The fusion nucleus then divides into four short rods, in the 

 case of rough bacilh, and two in the case of the smooth bacilli. These rods 

 appear to represent the nuclear units taking part in the fusion. One rod is 

 enclosed in the developing spore, which appears as a clear area of cytoplasm, 

 bounded by an obvious spore wall. The remaining one or three nucleoids 

 are rejected. They may be absorbed into the cytoplasm or may be discarded 

 upon the dissolution o( the sporangium, which follows the maturation of the 

 spore. This constitutes the reduction process, and is reminiscent ot the 

 ehmination of the polar bodies in mammalian oogenesis. 



The longitudinal rod torm of the nucleus may be retained tor a short 

 time in the maturing spore, but eventually a typical, eccentrically staining, 

 resting nucleus is produced. 



The spore is thus haploid, and the vegetative generations which arise 

 from it are similarly haploid. The diploid generations are those which occur 

 between the sexual process and the production of the spore. They arc probably 

 few in number. 



A second and more detailed account ot the reduction process in sporulation 

 is given by Allen et al. (1939). It differs from that agreed by most other 

 workers, but as it is well substantiated, may represent a parallel method, less 

 commonly found. The bacillus studied by these workers produced nuclear 

 figures, immediately before the production of the spore, which resembled 

 classical meiosis as it occurs in plant and animal reproductive cells. The 



