4/o 



THIRD PART. BACTERIA OR SCHIZOMYCETES. 



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become aggregated in the water into slimy masses a foot in depth. The gelatinous 

 matter is at first colourless, but may assume a colour varying from brick-red to dark 

 brown by admixture of hydrated oxide of iron. When grown in bog-water the cocci 

 develope into rods or filaments (1i) of unequal thickness, which at a certain age become 

 invested with a continuous thin but firm gelatinous sheath with the same admixture of 



iron as is found in the 

 jelly of the zoogloea-forms. 

 The single rod-like cells 

 within their sheaths pass 

 by repeated transverse bi- 

 partitions into the form of 

 nearly isodiametric mem- 

 bers, which then round 

 themselves off. The mem- 

 bers in the thicker filaments 

 often assume a flat disk-like 

 shape, and then divide into 

 2-4 small cells by walls 

 parallel to the longitudinal 

 axis of the filament. Both 

 these cells and the rounded 

 members of the slenderer 

 filaments ultimately escape 

 in the form of cocci from 

 the sheath, being set free 

 partly by the swelling of 

 the sheath along its whole 

 length, partly by its rupture 

 at the apex (r). In the 

 latter case some of the cocci 

 slip of themselves out of the 

 opening in the sheath, while 

 others are passively thrust 

 out of it by the growth in 

 length of the other parts 

 which remain in the sheath. 

 The cocci may, though they 

 rarely do, become motile, 

 and pass again out of this 

 state into the resting zoo- 

 gloea-form; they also de- 

 velope once more into rods 

 and filaments in the manner 



which has already been described. In addition to these forms curved spirilla-like 

 forms are also found, which may also break up into pieces, but without passing, as 

 far as has been at present observed, into the motile state. 



FIG. 196, Craiothri* fCiihtiiana. a ^ccccior sporaj. ce cocci dividing, /"cocci 

 collected into a group and connected together by a gelatinous substance ('zoo- 

 gloea'),the contour dark, h a group of cocci developing into filaments. rfilaments 

 of various forms and stoutness attached below to a substratum ; m r show the for- 

 mation of the common sheath round the single members ; q and n separating above 

 into members ; r with the upper members becoming successively broader and com- 

 paratively shorter, the uppermost members having separated by longitudinal divisions 

 into round spores ('cocci'), which have escaped at the upper end from the sheath. 

 cocci-zoogloeae. After Zopf. f natural size, the rest magn. 600 times. 



