i8 SULPHUR BACTERIA 



The buds, when quite small, are abstricted from the parent 

 organism, each usually containing a single sulphur granule 

 (Fig. 35). They are found in the surrounding medium in 

 aggregated masses, and are devoid of movement. Without 

 the proof supplied by the organic connection of the buds 

 with the parent organism they would ordinarily have been 

 regarded as a species of Lamprocystis. 



Although pure cultures of Thioporphyra volutans have not 

 yet been obtained it is possible to intensify its growth in an 

 artificial medium (see p. 62), which in consequence of its 

 growth becomes tinted purple. The individuals, however, 

 are much smaller in size. They vary from cocci of lO/x in 

 diameter (the normal size) to small globules that are only 

 if/i, in diameter. With sufficient assiduity it would have 

 been possible to arrange the cocci in a descending series in 

 which any particular form was a fraction of a /a smaller than 

 the preceding unit, until the minimum of if /a had been reached. 



A further proof of pleomorphism was supplied by Chro- 

 •niatium Linsbaueri, which was found in a small pool of water 

 in the Epping Forest, near London. The normal form of the 

 organism is ovoid, and it was this type of structure that was 

 presented in all but one of the samples that were periodically 

 sent to the writer. In the exceptional sample, however, 

 it was found that about 10 per cent, of the individuals were 

 spiral-shaped. As the general structure and colour of this 

 organism are of a very distinctive nature, and as the two forms 

 were absolutely alike in every other respect except that of 

 shape, there was every reason for the conclusion that both 

 were variants of the same organism (see Fig. 30 C). 



Although the organism Cladothrix dichotoma is not one of 

 the sulphur bacteria, it is sufiiciently closely related to regard 

 evidence of pleomorphism in it as contributary evidence 

 of pleomorphism in the sulphur bacteria. The threads of 

 Cladothrix dichotoma were observed in a particular solid 

 medium culture to be violently agitated, and to break up into 

 spirally wound fragments of short lengths, each of which 

 developed polar cilia. Intercalary fragments were observed 

 to " sidestep " from the threads, assume a spiral form, and 



