THE BIOLOGY OF BACTERIA 1/ 



and numbering about 4772 billions. Favourable conditions 

 do not occur, fortunately, to allow of such increase, which, of 

 course, can only be roughly estimated. But the above figures 

 illustrate the enormous fertility of micro-organic life. When 

 we remember that in some species it requires 10,000 or 15,000 

 fully grown bacilli placed end to end to stretch the length 

 of an inch, we see also how exceedingly small are the in- 

 dividuals composing these unseen hosts. 



Spore formation may result in the production of germinat- 

 ing cells inside the capsule of the bacillus, endospores, or of 

 modified individuals, arthrospores. The body of a bacillus, 

 in which sporulation is about to occur, loses its homogeneous 

 character and becomes granular, owing to the appearance of 

 globules in the protoplasm. In the course of three or four 

 hours the globule enlarges to fill the diameter of the rod, and 

 assumes a more concentrated condition than the parent cell. 

 At its maturity, and before its rupture of the bacillary cap- 

 sule, a spore is observed to be bright and shining, oval and 

 regular in shape, with concentrated contents, and frequently 

 causing a local expansion of the bacillus. In a number of 

 rods lying endwise, these local swellings produce a beaded 

 or varicose appearance, even simulating a streptococcus. In 

 the meantime the rod itself has become slightly broader 

 and pale. Eventually it breaks down by segmentation or 

 by swelling up into a gelatinous mass. The spore now 

 escapes and commences its individual existence. Under 

 favourable circumstances it will germinate. The tough cap- 

 sule gives way at one point, generally at one of the poles, 

 and the spore sprouts like a seed. In the space of about 

 one hour's time the oval refractile cell has become a new 

 bacillus. One spore produces by germination one bacillus. 

 Spores never multiply by fission, nor reproduce themselves. 



Hueppe has stated that there are certain organisms (like 

 leuconostoc, and some streptococci) which reproduce by the 

 method of arthrospores. Defined shortly, this is simply an 



