D. B. WARD, M. D. 191 



found frequently in sewers and ditches. The bacteria 

 are propagated in two ways : first, by fission, or simply 

 spliting apart ; hence they are known sometimes as the 

 fission fungi. When a bacillus, for example, attains the 

 maximum length of the species to which it belongs, it 

 breaks in two in the middle and becomes two bacilli. 

 Some species have a tendency to grow very long before 

 the separation occurs, when it breaks up into many Indi- 

 vid unl bacilli. One species growing in that way — the 

 bacillus subtilis— is very common in the city water at 

 present. This reproduction by fission is exceedingly 

 rapid and we can readily see how, under favorable cir- 

 cumstances, an enormous number of organisms may be 

 developed. Prudden says that an eminent biologist has 

 calculated that if the proper conditions could be main- 

 tained the progeny of a single organism 1.1000 of an 

 inch in length would in five days fill all the oceans of 

 the earth to the depth of one mile. 



The other mode of reproduction is by the formation of 

 spores. The spores appear in some part of the organism, 

 sometimes in the middle, sometimes at the ends. The 

 organism which causes that horrible disease tetanus, or 

 lockjaw, has a spore at one end so that the bacillus looks 

 like a nail or pin with round head. As in all the lowly 

 organisms which produce spores— the fungi, algfe, etc, 

 — these spores are much more resistant to unfavorable 

 conditions than are the mature plants. They will stand 

 a higher temperature and will not die if dried, but re- 

 main ready to spring into life and activity under more 

 favorable conditions of temperature and moisture. As 

 these organisms are omnipresent — in the air, in the water 

 — everywhere, and as some of them are the particular 

 enemies of our race, a great deal of serious and intelli- 

 gent thought has been given of late to the subjects of 

 fumigation and disinfection. This is too large a subject 

 to deal with in this paper and I shall therefore omit it. 



12Q 



