322 ANIMAL BIOLOGY 



from contact with their fellows rarely take cold despite 

 their exposure. On the other hand, colds are often con- 

 tracted when there has been no exposure to cold at all. 



A little attention to the subject will bring home to us 

 how many are the ways in which the germs of colds 

 and other diseases may be transferred from one person 

 to another. The afflicted person may cough or sneeze 

 and send into the air a multitude of germs which may be 

 breathed in by other people. Most infections, however, 

 are probably carried by the hand-to-mouth method. A 

 person with a cold for instance, by the frequent use of a 

 handkerchief, inevitably transfers the germs that abound 



FIG. 223. Forms of disease-producing bacteria, a, typhoid; 6, staphy- 

 lococcus; c, tuberculosis; d, diphtheria; e, syphilis; /, plague. 



in his mucous secretions to his hands. He may shake 

 hands with another person or handle some object that 

 the other person touches. The latter may eat some food 

 that he handles or otherwise bring the germs on his hands 

 in contact with his mouth and thus the transfer is made. 

 Door knobs, straps in street cars, or any objects commonly 

 handled by several people afford excellent means for the 

 transfer of the germs of disease. If one has been exposed 

 to any of these sources of contagion, especially during a 

 time when colds or other infections are prevalent, care 

 should be taken not to eat before the hands are thoroughly 

 washed. It is well to avoid people with colds whenever 

 possible, and the sufferer should bear in mind the possi- 



