58 MICROBES AND TOXINS 



limited by the quantity of available nourishment and by the 

 accumulation of the products of excretions ; the cultures end 

 by poisoning themselves. But even in a drop of culture 

 medium, the energy of multiplications is enormous. One 

 filament of the Bacillus ramosus studied by Marshall Ward 

 doubled its length in thirty-five minutes ; in twelve hours a 

 single bacillus produced four millions, and one piece of one- 

 hundredth of a millimetre in length produced in twelve hours 

 the equivalent of a thread of 40 metres. Pasteur followed 

 under the microscope the growth of the yeast of wine in grape 

 juice at 13 C. One globule produced 10 millions in twenty- 

 four hours when nothing intervened to limit its development. 

 It is easy to understand now how the infinitely minute grows 

 to form a mass and brings into play enormous forces. 



Spores. Certain bacteria produce spores, the spore appearing 

 as a shining point in the filament ; the protoplasm of the cell 



diminishes as the 

 spore increases, as 

 if speculations 

 were a condensa- 

 tion of the living 

 matter. Later the 



rWUZ&tS CftfoSpon bacillus disappears 

 and the spore is 

 free. Being en- 

 closed in a resist- 

 ing sheath the 

 FIG. 27. Various types of germination of spores. i i 



I/The spore germinates by growth hi all S P Ore resembles a 

 dimensions. 2. Germination by a sort of Seed, capable of 

 terminal budding. 3. The spore germinating Dro longed D r e - 

 by a sort of lateral budding. (After De Bary 

 and Prazmowski.) servation and of 



sprouting into a 



new bacillus when the conditions become favourable. It is 

 by means of their spores that the . bacilli of tetanus and of 

 anthrax persist so tenaciously in nature. The anthrax bacillus 

 is killed by heating to 60 C., the pore not till after three 

 minutes' boiling at 100 C, 





