THE GENERA CRENOTHRIX AND CLADOTHRIX 273 



forms already described. ZOPF (VI.) observed that in many cases this occurs 

 before they have quitted the sheath of the parent thread ; and in this manner 

 tufted forms, similar to that shown in Fig. 66, are produced. Otherwise, the 

 sheath is gradually emptied of 

 its contents, and then collapses 

 limply and withers up. 



If we disregard the excep- 

 tions just named, wherein the 

 germination of the cocci pro- 

 ceeds within the parent thread, 

 and so causes it to present a 

 branched appearance, it may be 

 said that the genus Crenothrix 

 appears only in the form of 

 single, unbranched, filamentous 

 chains of cells. This charac- 

 teristic suffices to distinguish 

 this genus from that bearing 

 the name of Cladothrix, the 

 best-known species of which is 

 Cladothrix dichotoma. As this 

 name implies, we have here to 

 do with a forked thread, such 

 as shown in Fig. 67. This 

 false branching is produced in 

 the following manner : One 

 of the rod-shaped joints of 

 the thread turns aside, and, 

 growing beyond its next higher 

 neighbouring cell, repeatedly 

 subdivides and forms a new >{. ^N 



thread, on which a similar false 

 branching may also develop. 

 Hence there ensues a forma- 

 tion the internal structure of 

 which is represented diagram- 

 matically in Fig. 68. In many 

 species (not depicted here) 

 the sheath becomes greatly 

 thickened at the base, where 

 it attains a diameter many 

 times exceeding that of the 

 cells it encloses, but tapers oft' 



gradually towards the free ex- n _ 2 . macrococci, and r. micrococci splitting off. Magn. about 

 tremity. Cladothrix dichotoma 600. 



aln rliffpr.! from +>IA ahnvp a-e. reproduction of the cocci ;/. colony (zooglo3a) of cocci ; 



also dittero trom the above- ^ ^^ uatura , gize . h game beginnin ,, to gc rminate. 



mentioned thread bacteria in Magn. 600. (After Zopf.) 



another important particular, 



viz., by the production of rod-shaped roving cells, called rod gonidia. which 



develop at the extremity of the threads, and, after being initially embedded in 



the swollen sheath (Fig. 69), are liberated, wander about, and finally settle down 



to form new threads by subdivision and sheath-formation. 



Allied to Cladothrix dichotoma though not, as ZOPF (VII.) opined, belonging 

 to the morphological cycle of this organism is Leptothrix ochracea, which was 

 i s 



FIG. 65. Crenothrix polyspora 

 thread forms of different diameter. 



