486 FISSION FUNGI WITH VARIABLE VEGETATIVE FORMS. 



organisms arranged together in the following pages, 

 these organisms differing from the bacteria as yet 

 described in their natural habitat, in their size, in their 

 morphological characters, and in many biological 

 characters; these organisms were, up till a few years 

 ago, reckoned by most authors among the algse. Zopfs 

 results are reproduced here without any commentary, 

 although they have not as yet been confirmed by control 

 investigations. A repetition of his observations is, 

 however, so much the more desirable, as the methods 

 employed offer no sort of guarantee that he was dealing 

 with trustworthy pure cultivations, and also as the mode 

 in which the various vegetative forms of each variety are 

 designated does not always appear to be sufficiently well 

 founded. 



To this group belong the organisms included in 

 groups 3 and 4 of Zopfs classification, the leptothrix 

 and the cladothrix forms. In the series of leptothrix 

 varieties, the genus leptothrix has been omitted here for 

 the reasons mentioned on page 180, so that the genera 

 crenothrix, beggiatoa, phragmidiothrix, and cladothrix 

 are alone described. For the generic characters see 

 page 180. 



Crenothrix Kulmia n a . 



Crenothrix. This organism was discovered by Kulm, and has been 

 investigated by Cohn, and later by Zopf. It is one of 

 the most frequent aquatic fungi, and occurs in stagnant 

 and flowing water ; it is sometimes present in such 

 large quantities in the water pipes in many places 

 (Berlin, Lille) that the water is quite unfit for use. It 

 can be artificially cultivated in decoctions of dead algae, 

 or in decoctions of animal substances, such as swine's 

 bladder. 



Morphological According to Zopf the fungus shows coccus, rod, and 

 ehaiacters. tliread f orms . The cocci are spheres 1 to 6 ^ in 

 diameter ; their membrane becomes gelatinous, and 

 they multiply by fission. By this mode of multiplica- 

 tion, and by the gelatinous character of their membrane, 



