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SULPHUR BACTERIA 



Laniprocystis is compared with those of an organism such as 

 Beggiatoa alba, which hves in a medium rich in organic matter, 

 the contrast is so great that it is scarcely possible to imagine 

 two organisms at this phase of existence that are so diamet- 

 rically opposed. 



The general conclusion is drawn that the coloured and the 

 uncoloured forms began their present stage of existence as 

 coloured, and as uncoloured organisms, respectively, and that 

 in their further development colour has played no part. 



F. Reproduction. — In all the sulphur bacteria which have 

 been investigated the prevailing method of reproduction is a 



Thiovulum 



Thiop hysa 



Chrotnatium 

 Thio porphyra ^ 

 Achromatium 



Thiospirillum -«— 



(Rhodo-thiospirillum) 



Thiopedia -*- 



I 



Thiosarcina 

 (Rhodo-thiosarcina) 



Primitive hi ghly 

 pleomorphic or g -anism 



Filament 



Coccus 



Rod form - 



— Spiral form 



Filament in 

 zoog-loea condition 



_ Coccus in 

 zoogloea condition 



Rods in 

 zoog-loea condition 



Fig. 64. 



^Beg giatoa alba 

 Thiothrix 



■^^»- Thiobacillus 

 ^Thiopseudomonas 



^_^ Thio ploca 

 -^ Rhodocapseae 

 — -^ Th iocap s e ae 

 ^^ Thiosphaerion 



Thiobacillus 



Bovistus 



simple fission followed by the growth of the separated portions. 

 This method is followed even in such organisms as Beggiatoa 

 alba, in which the cell has a slightly differentiated peripheral 

 layer. In Beggiatoa mirabilis the formation of a new cell is 

 preceded by the development of a transverse cell membrane 

 as in the higher plants. This, however, is not associated with 

 any other complexity in Beggiatoa mirabilis, notwithstanding 

 its relatively gigantic size. 



The occurrence of structures that may be endospores in 

 Beggiatoa alba and in Thioporphyra vohitans is at present too 

 problematical for discussion. 



