4 66 



THIRD PART. BACTERIA OR SCHIZOMYCETES. 







i 



The removal of the transversely-opened membrane is the best and only certain 

 demonstration of the fact that the spore is actually invested with a special membrane. 

 This membrane is easy of observation, especially in cultures in very flat drops of the 

 fluid. It sometimes divides quite across into two halves, which are attached at first 

 like caps to the extremities of the elongating rod and are afterwards torn from them. 

 I often failed to observe the final removal of the membrane in larger quantities of the 



fluid. There each cap, distinguished by its more 

 sharply defined outline, was seen to be attached to 

 the extremities of the growing spore and gradually 

 ceased to be distinguishable ; it would seem therefore 

 that in these cases the membrane, after splitting trans- 

 versely, is not removed from the spore in connected 

 pieces, but swells up or is dissolved and so disappears. 

 The membrane often clings to the rod-cell which has 

 slipped out of it in such a manner that the longer 

 diameters of the two bodies cross one another, and 

 hence the appearance is produced as if the growth 

 in length in germination is in a direction at right 

 angles to the longer diameter of the spore or parent- 

 rod ; but this is not really the case. 



The species which we are considering occurs 

 also in another form, namely in long curved chains, 

 in which a segmentation of the smooth cylindrical 

 rods is only obscurely distinguishable, while the 

 isodiametric cells on the other hand are distinctly 

 defined, are slightly swollen and protuberant, and are 

 in many cases themselves curved at the points of 

 greatest curvature. Torulose chains of this kind or, 

 to use the terminology noticed above and founded on 

 growth, cocci grouped in rows, are usually developed 

 in great abundance, being loosely intertwined into 

 thick convoluted masses and sometimes breaking up 

 here and there into separate cells. They are motionless 

 or show a very slight movement. There was little 

 or no formation of spores. I almost invariably dis- 

 covered this form when the cultures were rendered 

 impure by other small Bacterium-forms, but the 

 Bacillus formed the majority. It may be a question 



how far this fact points to the cause of the appearance of the torulose chains, 

 but it is certain that they become transformed into the even rods when the culture 

 is pure. 



The cells of the Bacillus of anthrax, B. Anthracis, Cohn (Fig. 195 A), ap- 

 proach i /* in thickness in vigorous specimens grown in the blood of animals attacked 

 by it, and grow to about 3-4 times that length. They are connected together in the 

 blood into straight rods of different lengths ; in cultures on some suitable dead sub- 

 stance they form long pluricellular filaments ; these may be much twisted or bent into 



FIG. 195. A Bacillus Anthracis. 

 Two filaments grown on a microscopic 

 slide in a solution of meat-extract, partly 

 in an advanced state of spore-formation ; 

 at the top two ripe spores which have 

 escaped. The spores are drawn some- 

 what too narrow ; they are nearly as 

 broad as the transverse diameter of the 

 mother-cell. B Bacillus subtilis. i. 

 fragments of a filament with ripe spores. 

 2. spore beginning to germinate; the 

 outer wall ruptured transversely. 3. 

 young rod projecting from the wall of 

 the spore in the usual transverse 

 position. 4. Germ-rods curved in a 

 horse-shoe shape and with the extremi- 

 ties connected ; one of them with one 

 extremity subsequently released. 5. 

 Germ-tubes with the two extremities re- 

 maining connected and already greatly 

 increased in size. Magn. 600 times. 



