THE BLOOD AND ITS FUNCTIONS 135 



siderable money for the warfare against mosquitoes. Since 

 mosquitoes breed in stagnant water, the draining of such 

 breeding pools or the pouring of kerosene on the surface is an 

 efficient method of killing the young. Everyone for his own 

 good, as well as for the good of others, should give all the 

 assistance he can to this work of mosquito extermination. 



Influenza. While this disease is doubtless acquired by 

 breathing in the organisms causing it, it manifests itself prim- 

 arily as a disturbance of the blood in the form of a fever. As 

 is well known, it is extremely contagious, and thus easily 

 assumes the proportions of an epidemic. It differs from an 

 ordinary cold by spreading even more rapidly, in causing a 

 person to feel suddenly weak, experience pain in the head, 

 back or eyes, develop a fever and "feel sick" to a greater 

 degree. As to its cause, several bacteria have been recog- 

 nized as present, and the practice of inoculation against the 

 disease has been begun with fairly successful results. How- 

 ever, immunity is very transitory, and one may "catch" 

 influenza repeatedly. Fatal results seldom accompany the 

 malady by itself, but it leaves the system weakened and 

 susceptible, so that other more serious diseases, e.g. pneu- 

 monia, are very liable to follow. Extreme care while con- 

 valescing should be observed. 



Influenza is doubtless spread by the "droplet method;" 

 i.e. a healthy person breathes in minute moisture droplets, 

 containing the germs, which have been expelled by a sick 

 or near-sick person while sneezing, coughing, talking, or sing- 

 ing. One should avoid crowded rooms, cars, public gather- 

 ings of all kinds, and contact with the sick; also spend as 

 much time as possible in the open air in recreative exercise. 

 If attending those sick with influenza, one should always 

 wear a gauze cloth over the nose and mouth as a precaution. 



