490 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS. 



Beggiatoa 



rosep- 



persicina. 



Identical with 

 the species 

 formerly de- 

 scribed as 

 Clathrocystis 

 roseo- 

 persicina. 



Beggiatoa 

 inirabilis. 



of cilia at each end. These swarming spirals were formerly 

 described as ophidomonas (see page 484). The spiral threads 

 show the same division into rods and cocci as the straight 

 threads, but this is more difficult to demonstrate, and can only 

 be done by the aid of reagents. 



Beggiatoa roseo-persicina. Frequent in impure ditches and 

 ponds, covering the substratum with a red or violet deposit. 

 Often observed on the Danish sea-coast. In the thread stage 

 it can only be distinguished from B. alba by the reddish- violet 

 colour. The cocci formed in the threads develop by con- 

 tinuous subdivision into peculiar zooglaea, which are lobulated, 

 branched, or in the form of a network. Eods develop under 

 certain circumstances from the cocci in these colonies, and after 

 solution of the gelatinous sheath the rods and cocci can 

 swarm. The rods form threads, and these may show a partial 

 or a total spiral formation like B. alba. 



The retif orm zooglaea formation of B. persicina was formerly 

 described as Clathrocystis or Cohnia roseo-persicina, and by 

 Lankester as "peach-coloured bacterium."* The cells are 

 spherical or oval, of a reddish colour, and as much as 2'5 /*. 

 in diameter ; they form at first solid families bound together 

 by gelatinous material ; at a later period hollow bodies appear, 

 filled with watery fluid, and as much as 660 /*. in diameter ; 

 in these bodies the cells form a single peripheral layer. The 

 bladders are often torn or riddled with holes, and then they 

 have the form of a delicate network, which ultimately breaks 

 up into irregular bunches. 



The red colouring matter which is present in the cells 

 differs from other colouring materials and is termed bacterio- 

 purpurine ; the same pigment is also contained in some of the 

 species of monas mentioned below, but it is quite different 

 from the colouring matter of micrococcus prodigiosus. 

 Bacterio-purpurine is of a peach- red colour, is insoluble in 

 water, alcohol, &c., and shows under the spectroscope great 

 absorption in the yellow and less in the green and blue, and 

 also cloudiness in the more highly refracting half of the 

 spectrum. No chlorophyll substratum is contained in the 

 colouring matter. In the cells, especially in old cells. 

 dark granules can be observed which consist of reguline 

 sulphur. 



Beggiatoa mirabilis. This organism occurs in sea-water, 

 forming whitish deposits on decomposing alga?, sea-weed, &c. 

 It is distinguished from tlie other beggiatoa by its large 

 transverse diameter 30 p. The threads show segmentation, 

 at first into almost isodiametric pieces, and then into short 



* Eabenhorst- Winter, Lit., p. 1. Cohn, Beitrage, i., Part 3, p. 157. 

 Lankester, Quart, Jovrn. of Micr. >c.. 1873, vol. 13, p. 408. 



