TEXT-BOOK OF BACTERIOLOGY. 205 



of bouillon, the decided tendency of this species to produce zooglcea 

 rolled up into curly bundles was remarked, and the same thing is 

 here once more presented. 



It is well worth while to make print preparations of such sur- 

 face colonies by pressing- the cover-glass upon the colonies as 

 already described. Even with a low magnifying power they have 

 an extremely elegant, characteristic appearance with their polyp- 

 like branches and continuations; and if we call in the aid of oil 

 immersion, we perceive that the blue or red stained, curiously- 

 interlaced markings of the print resolve themselves into unbroken 

 rows of separate, closely-pressed rods, lying side by side in regular 

 order like so many bricks. 



It is very similar on the agar plate. The surface of this medium 

 becomes covered in twenty-four hours with numerous colonies, in- 

 tricately interlaced with the most peculiar arabesques, which fre- 

 quently unite and run into each other like a fine-woven texture. 

 After a short time the spore-formation also begins, and the interior 

 of the small pure cultures then takes a granulated, shagreened 

 appearance. 



In the puncture or stab cultivation the anthrax bacillus also 

 grows very characteristically. All along the puncture, fine white 

 threads penetrating into the gelatin are seen, which as the} 7 ad- 

 vance branch out or unite with each other, and in some places 

 appear like bunches of the finest bristles or prickles. The liquefac- 

 tion of the culture medium advances slowly, beginning from the 

 free surface. Here a thick, slimy, white layer appears, consisting 

 of bacteria which gradually sink to the bottom by their own weight 

 as the softening of the gelatin advances. The bacilli having no 

 locomotive power cannot rise again, and so it happens that older 

 cultures present a very peculiar appearance. The upper portion of 

 the gelatin is completely liquefied, but clear and free from all ad- 

 mixture, and without any film on its surface; lower down, where 

 the still solid part of "the gelatin forms a definite limit, the closely- 

 felted mass of the culture lies in whitish clouds and flakes; below 

 these may generally be seen the remainder of the puncture still 

 preserved with its small, elegant, thorn-like projections. 



On the surface of the obliquely-hardened agar the anthrax 

 bacillus grows as a grayish- white, tough coating which shines like 

 tarnished silver, and may be peeled off in long strips. 



Blood-serum is slowly liquefied; yet the bacterial growth here 

 offers nothing worthy of remark. 



This bacillus grows luxuriantly on boiled potatoes. It spreads 

 out as a creamy-white, tolerably dry coating over the slice, and 



