396 BACILLI WHICH DO NOT CAUSE FERMENTATION. 



The newly formed rod always stands at right angles to 

 the long axis of the spore; but the long axis of the 

 newly formed spore is the same as that of the rod in 

 which it develops; hence, as the result of the spore 

 formation, there is an alteration in the direction of 

 growth of the bacilli.* 



Bacillus subtilis is Very widely distributed; its spores 

 are present in the air, in dust, on the surface of all 

 kinds of articles, and they occur only too often as un- 

 desired impurities in cultivations of other organisms. 

 It forms a white efflorescence on the dung of herbi- 

 vorous animals; on liquid dung it forms, thick wrinkled 

 skins. This organism grows on a great variety of 

 nutrient substrata, even when they only contain a little 

 organic material; it grows in fluids jut as well as on 

 solid but moist substrata; a markedly acid reaction of 

 the media interferes, however, markedly with its develop- 

 ment. A cultivation of this bacillus, to some extent 

 pure, is most easily obtained by infecting the ordinary 

 nutrient solutions with a little dust from hay, or by 

 employing an infusion of hay as a nutrient solution; in 

 the latter case the fluid is boiled for about- a quarter of 

 an hour; as a result almost all the other fission fungi 

 are killed, and only the extremely resistant spores of 

 bacillus subtilis retain their vitality. 



According to Buchner, in order to obtain bacillus 

 subtilis with certainty, it is best to allow hay to stand 

 at 36 C. for four hours with extremely little water, then 

 to pass it .through a fine sieve, to dilute the water to a 

 ' specific gravity of 1004, and then to raise about 500 cm. 

 of this mixture to the boiling point in a vessel closed 

 with cotton-wool, the heat being continued for one hour, 

 and only very little steam being developed ; after it has 

 been boiled the fluid, if kept at 36 C., shows a scum 

 on the surface after 48 hours, consisting of bacillus 

 subtilis. It is only when the reaction is very markedly 

 acid that it is necessary to neutralise the material before 

 boiling it. 

 Cultivation 011 ^ n g elatme plates bacillus subtilis forms small whitish 



* After Brefeld, JBotan. Unters., Part 4, and Prazmowski, Lit., p. 47. 



