410 BACILLI OF NO KNOWN PATHOGENIC PROPERTIES. 



is luxuriant, there are usually two or three completely formed 

 spores and some imperfect ones. This organism was found 

 by Koch on putrefying vegetable infusions, on which it forms 

 a thick gelatinous skin. 



Bacterium merismopedio'ides (Zopf). 



This organism was found by Zopf in a decoction of stinking 

 mud from the Panke river. " It forms threads which are 

 not constant as regards thickness, but vary between 1 and 

 1'5 fM. They divide in the first instance into long rods, then 

 into short rods, and finally into cocci. It is clear that as the 

 threads have varying diameters so the cocci must vary 

 correspondingly in size. The latter become free, and then 

 show active movement. When they come to rest they form 

 on the surface of the water masses or superficial scums, as the 

 result of continued division in one direction ; and later, as the 

 result of division in two directions, the very characteristic 

 ' tafel ' colonies are produced, which are morphologically quite 

 similar to the little tablets of the merismopedic state of the 

 phycochromaceae. These colonies consist of 64 x 64 cells or 

 more. Their walls become gelatinous as time goes on. When 

 the colonies are numerous, and in close contact with each 

 other, their gelatinous sheaths run together, and thus we 

 have a continuous zooglaea which always forms a thin scum 

 on the surface of the water. The cocci swarm under suitable 

 nutrient conditions (in fresh mud decoction) out of the tablet 

 zooglaea, and again develop to rods and threads." The de- 

 scription given by Zopf, and the fact that the cultivations 

 were exclusively carried 011 in fluid media, give rise to the 

 suspicion that the observations depend on the presence of 

 ji mixture of various kinds of bacteria. 



