RELATION OF PATHOGENIC TO SEPTIC BACTERIA. 33 



gelatine pork becomes liquefied without there having occurred 

 a trace of spore formation in any part of the gelatine material. 

 But I have seen a cultivation in Avhich spore formation never- 

 theless appeared subsequently, although the bacillus mass has 

 become deeply placed in the fluid gelatine. In this case the 

 same process occurred as is mentioned above to have happened 

 in a test-tube of pure pork broth, viz. bundles of threads 

 grew along the glass wall of the test-tube towards the surface 

 of the liquid, and having reached this spores made their 

 appearance. 



Spore formation can be, however, easily procured and kept 

 up in gelatine pork in this manner: A flask containing gelatine 

 pork, for about a quarter or a half of its volume, is inoculated 

 with the Bacillus anthracis in the middle of the surface of 

 the solid gelatine material. The growth naturally spreads 

 from here to all parts of the surface, since growth in this 

 direction is much easier than into the depth owing to the 

 resistance offered by the solid material. The layer of gelatine 

 on which the growth takes place becomes liquefied, and thus 

 the growth passes downwards. Owing, however, to the large 

 surface presented by the gelatine material, the bacillus threads 

 show very copious spore formation, and this spore formation is 

 kept up by the bacillus threads for a long time, since even 

 when the superficial layer of the gelatine has become liquefied 

 the bacillus mass is still near a very large surface of air. This 

 superficial fluid layer can be easily drawn off with a glass 

 pipette drawn out into a thin tube at one end, which is intro- 

 duced into the flask through the cotton-wool plug, in the same 

 manner as for the purpose of withdrawing a single drop, or of 

 inoculating it in the first instance with some seeds, a method 

 that has been minutely described above. This liquefied mass 

 thus drawn off teems with bacillus threads and spores, multi- 

 tude of them being quite isolated. It can be easily discharged 

 into a sterilised test-tube plugged with cotton-wool, without 

 contamination with air organisms, and kept here ad infinitum. 

 The fluid mass being nearly or quite exhausted of the nourish- 

 ing parts, at any rate for the Bacillus anthracis and its 



VOL. XXIII. NEW SEtt. C 



