536 



DESCRIPTION OF SPECIES. 



floats on the surface. The liquefied 

 gelatine, at first turbid, becomes 

 clear as the bacilli settle at the 

 bottom of the tube. 



On agar a wrinkled film develops, 

 and also on serum. 



Fig. 213. Pure-cultoke of Bacillus 

 subtilis on the sukface op nu- 



TBIEUT AGAE. 



On potato the growth is white, 

 and there is copious spore-forma- 

 tion. 



On ordinary nutrient liquids they 

 develop at first a thin, and subse- 

 quently a thick, dense, crumpled 

 pellicle, with copious spore-forma- 

 tion. 



The simplest way to obtain a 

 .culture of the bacillus is to make 

 a decoction of hay. The hay is 

 chopped into small pieces, and 

 boiled with distilled water in a 

 flask for a quarter of an hour. 

 The infusion is then filtered into a 

 beaker, covered with a glass plate, 

 and set aside in a warm place. In 

 two or three days the liquid swarms 



with the bacilli, the spores of which 

 exist in great numbers in ordinary 

 hay. A more sure method for 

 obtaining a pure cultivation is as 

 follows : — 



(a) Add only a small quantity of 

 water to some finely chopped hay, 

 and set aside for four hours at 

 36° C. 



(6) Pour ofE the extract, and 

 dilute it to the sp. gr. 1-004. 



(c) Boil gently for one hour in 

 a bulb plugged with cotton wool. 



(d) Set aside 500 ccm. of the 

 extract at 36° C. 



In about twenty-four hours, as 

 a rule, a pellicle has commenced 

 to develop upon the surface of the 

 liquid. If the reaction is definitely 

 acid, carbonate of soda solution 

 must be added to the decoction. 



Methods of Staining Hay Bacillus. 



To demonstrate the flagella o£ the 

 bacilli, they may be stained with 

 haematoxylin solution (Koch), or by 

 Loffler's method. 



The linking together of cocci, long 

 rods and short rods in the threads, is 

 shown by treating with alcohoUc solu- 

 tion or f uchsine, or with iodine solution 

 (Zopf). 



To stain the spores the cover-glass 

 preparations must be heated to a very 

 high temperature (210°C. ), in the hot- 

 air sterihser for half an hour, or they 

 may be exposed for a few seconds to 

 the action of concentrated sulphuric 

 acid (Biiohner), or floated for twenty 

 minutes on hot solution of the dye. 



Bacillus subtilis similans. — 

 There are several bacilli closely 

 resembling Bacillus subtilis. 



Two have been isolated from 

 human fseces by Bienstock which 

 do not liquefy nutrient gelatine. 



No. I. Eods and filaments ; 

 spore-formation present. 



On agar they produce a delicate 

 wrinkled veil. 



No. II. Rods morphologically 

 identical with No. I. 



On agar they produce a smooth, 

 shining layer. 



Bacillus superficialis (Jordan). 

 — Rods 2 -2 fi in length, and '1 /i in 

 width ; singly, and in pairs. Motile. 



Colonies have a yellowish-brown 



