32 SEX IN A4ICROORGANISMS 



Using the technique so successfully employed by Robinow 

 (1942) in the demonstration of bacterial nuclei, Klieneberger-Nobel 

 (1949) has described cell and nuclear fusions in a number of different 

 bacteria. The process described was essentially as follows. Rods or 

 filaments break up into small cells designated primary cell units, each 

 of which consists of a nuclear granule surrounded by a thin layer of 

 cytoplasm. Fusion of two to many of the primary cell units occurs 

 when the cytoplasm of adjacent units coalesces. This is followed by 

 nuclear fusion which is said to involve the formation of "ramifica- 

 tions." Although the products of fusion, the L-bodies, are commonly 

 round, oval, or spindle-shaped, their size and shape may vary with 

 the number and arrangement of the cell units which fuse. These 

 L-bodies can develop further in an appropriate environment to pro- 

 duce normal-appearing rods. This type of process was reported to 

 occur in Bacteroides fzmdulifor7/?is, Streptobacilhis vwnilijorviis, and 

 a strain of Escherichia coli under normal cultural conditions; in Fro- 

 teus sp. under the influence of temperature changes; in E. coli- 

 vmtabile grown on nutrient agar containing lithium chloride; and in 

 E. coli-mutabile, Proteus sp., and Salmonella schottiniilleri grown on 

 penicillin-containing medium. 



Klieneberger-Nobel based her interpretations on this particular 

 study on dead organisms. Certain of these interpretations are not in 

 agreement with the results of later studies made directly on living 

 cells. Stempen and Hutchinson (1951a) observed that when cell 

 fusion occurred in Proteus vulgaris OX- 19 only two cells were in- 

 volved in each fusion observed. When E. coli is exposed to non-lethal 

 concentrations of penicillin (Pulvertaft, 1952), aberrant forms re- 

 sembling the L-forms of Klieneberger-Nobel are produced; however, 

 all the aberrant forms noted developed as distortions of single rods 

 which did not divide. 



CELL FUSION IN Proteus vulgaris OX- 19 



Cell fusion has been demonstrated in Proteus vidgaris OX- 19 by 

 the direct observation of living cells in slide cultures (Stempen and 

 Hutchinson, 1951a). The fusion process most commonly begins with 

 the appearance of a budlike structure at the junction of a pair of rods 

 attached end to end (Fig. 8). This bud becomes larger as the contents 

 of the rods pass into it (Figs. 9 to 11). The rods are soon "absorbed" 



