THE BIOLOGY OF MICROBES, ETC. 157 



mately the gelatine is liquefied. On agar-agar it 

 forms a viscid yellow layer ; while in test-tube 

 cultivations it liquefies the gelatine which becomes 

 cloudy. B. butyricus grows best between 35 and 

 40 C. It is the cause of the rancidity of butter 

 and the ripening of cheese. It decomposes cellulose, 

 and hence it is of great ' importance in the digestive 

 process of herbivorous animals, in whose stomachs 

 and intestines it is very common/ 



Bacillus ulna. This species is closely allied to B. 

 subtilis. It measures 10 X 2 /JL; and occurs singly, 

 in chains, but it does not form leptothrix. It gives 

 rise to spores which measure 2 '8 p x 1 p This 

 microbe is found in rotting eggs. On the surface 

 of bouillon it forms thick colonies which ulti- 

 mately unite, giving rise to a pellicle. It is readily 

 cultivated on sterilised egg-albumin. 



Bacillus of Symptomatic Anthrax. This microbe 

 is the cause of the infectious disease known as 

 quarter-evil, rauschbrand, charbon symptomatique, 

 etc. The disease affects cattle, giving rise to the 

 formation of an irregular tumour in the subcutaneous 

 and intermuscular tissues. There is high fever, and 

 death generally occurs in about forty-eight hours. 

 This motile microbe (3 to 5 p x 0'5 to 0*6 //,) is 

 found in the serous fluids, bile, tumours in this 

 disease. It has been cultivated in fowl broth to 

 which small quantities of glycerol and ferrous sul- 

 phate have been added. It also grows on blood 

 serum, nutrient gelatine, and vegetable albumin. 

 As the microbe is anaerobic, it must be cultivated 

 in an atmosphere devoid of free oxygen. It is best 



