Job 



CIVIC BIOLOGY 



Germs circulating in the blood are usuallv drawn off bv 

 blood-Slicking insects, ticks, or mites ; malaria and yellow 

 fever, by mosquitoes ; typhus fe^•er, by body lice (and per- 

 liaps by fleas and bedbugs) ; plague, b}^ fleas (possibly also 

 leprosy) ; typhoid, by bedbugs ; Texas fever and spotted 

 fever, by ticks; infantile paralysis (?) and anthrax, by the 



.Micrococci 



Bacilli 



S|>irilla 



bi.flnmmaCLoa 



(Pneu ni'jii'i'J, 



Rheumot.isrn, 



S'jvc.-i. Boils) 



Inflarivrnation 



(rt'lppC 



Diphthena 



Fig. 109. Pathogenic bacteria modeled to scale in plasticene (niicra = 

 centimeters), magnification of models being 10.000 diameters 



A suggestion for a laboratory oolleotion. INIount in inspot cases under glass. 



Photograph by the author 



stable fly ; and sleeping sickness, by one of the tsetse flies. 

 Diseases marked l\y lesions of tlie skin — measles, scarlet fever, 

 smallpox, and probably dandruff" and eczema — may escape 

 with the scales of cuticle or the contents of blisters or sores. 

 How living disease bacteria are carried. Tlie greatest barrier 

 to the learning of truth is apt to be a firm belief of an error. 

 Xo set of ideas has cost the world more misery, suffering, 

 and loss than false notions, prejudices, and superstitions re- 

 garding the transmission of diseases. First they were carried 



