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 millirnetre 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 bacteriaproducesporeSjthespore appearing 

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



diminishes as the 

 young spore increases, as 



bacterium if sporulations 



were a condensa- 

 tion of the living 

 matter. Later the 

 remoGisjf the spore bacillus disappears 

 and the spore is 

 free. Being en- 

 closed in a resist- 

 „ . , . . , ing sheath the 



r IG. 27. — Various types of germmation of spores. , , 



I. The spore germinates by growth in all spore resembles a 

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

 terminal budding. 3. The spore germinating nrnlnno-prl nrP 

 by a sort of lateral budding. (After De Bary Proiongea pre- 

 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 spore not till after three 

 minutes' boiling at iqo° C. 



