SF.X IN BACTERIA— I'AIDINCI' 1"R()AI iMORFIIOLOGY 3] 



L'oli (.Mellon, 1925) such spherical forms have been observed to one 

 side of the junction of two rods. Strands of w hat was considered to 

 be nuclear material were seen to extend into the round body from 

 the two rods. Although the nature of this material was not definitely 

 determined, the process was considered to be sexual in nature and 

 the round forms were called zygospores. 



Stoughton (1932) observed a similar phenomenon in Bacterkn/i 

 Vhihiicearimi. His attempts to study subsequent development of the 

 zygospores in living preparations were only partially successful, be- 

 cause the multiplication of the ordinary rods was found to be so 

 rapid as soon to overgrow the particular cell under observation. Thus 

 most of the results were derived from the study of stained films. 

 Other spherical forms in B. inalvacearinn (Stoughton, 1929) may 

 arise as the result of budding from normal or slightly s\^ollen or oval 

 cells which occur in cultures aged for about 6 weeks. 



The fusion of rods in pairs has also been described for a strain 

 o{ Bacteroides fimdulifoi'7jns (Smith, 1944). Organisms removed from 

 broth cultures at 3 -hour intervals were stained with Giemsa stain 

 without previous acid hydrolysis. During the first 6 hours the regular, 

 single rods contained granules which stained deep blue. At 9 hours 

 the rods had increased in length and were attached end to end in 

 pairs with the apposed ends swollen and filled with the deep blue- 

 staining material. Between 9 and 1 5 hours the swollen ends had appar- 

 ently fused so that the organisms appeared as long rods with a central 

 swelling. Between 18 and 21 hours the cultures consisted almost en- 

 tirely of large round bodies which presumably resulted from the 

 absorption of the rods into the central swelling. These round bodies 

 containing the deep blue-staining material in clumped or discrete 

 masses developed further by fractionating into ordinary rods, each 

 rod receiving a few granules of the deeply stained material. This 

 material was considered to represent a nuclear apparatus, although, 

 unfortunately, its nature was not experimentally characterized further 

 as, for instance, by the Feulgen reaction. 



Utilizing a fixing and staining procedure of proved value in 

 cytological investigations of higher organisms, Lindegren and Mellon 

 (1933) postulated a possible sexual mechanism in the avian tubercle 

 bacillus. From aceto-carmine-stained preparations they described the 

 fusion of nuclei from adjoining coccoid cells with the subsequent 

 growth and division of the zygote. 



