39 



outer twigs of the trees in bunches of several hundred eggs in each, 

 carefully varnishing the bunches to protect them from the weather 

 Destruction of these bunches or belts of eggs, or of the young cater- 

 pillars as soon as they are hatched, is the only practical mode of dealing 

 with them. 



Again, the same substances which destroy noxious insects are also 

 used in medicine as disinfectants, and the careful study of their action 

 will advance the cause of agriculture. The farmer who carefully apj 

 plies the right form of insecticide to his potato vines during the growing 

 season will insure the best crop. So, also, with his fruit trees; a care- 

 ful application of spraying liquid of such strength as not to injure the 

 trees, but strong enough to destroy the insect pests, will insure the best 

 crop of fair and handsome fruit. 



So the health officer who applies disinfectants judiciously and intelli- 

 gently will be rewarded in finding that scarlet lever, diphtheria and other 

 pests of mankind will not recur in the same household unless introduced 

 from outside sources. 



I cannot close this comparison without reference to the labors of one 

 man who has lately passed away from earth to his great reward, and 

 who was a common benefactor both of the medical profession and of 

 those who till the soil. lie was much more, he was a benefactor to the 

 whole human race. I mean Louis Pasteur. Born in the little town of 

 Dole, in France, of humble parentage, his father was a veteran French 

 soldier, afterward a tanner. The son Louis early in life became an 

 enthusiastic student of nature and of natural laws. More than a half 

 century ago he had begun the course of experimental research which 

 destined him to become one of the greatest allies of the medical profes- 

 sion and of agriculture that the world has ever known. 



One of his first triumphs was the discovery of the cause of the silk- 

 worm disease In 1819 and 1850 the silk-worms were attacked with a 

 parasitic disease which caused the loss to France, in the silk-worm in- 

 dustry alone, of 120,000,000 in a single year. The plague spread to 

 Spain and Italy, and finally no eastern country was exempt from its 

 ravages except Japan. Pasteur was urged to study the subject with 

 the view of finding the cause of the disease and its prevention. He 

 gave his whole attention to this question for nearly three years, and so 

 zealously did he pursue his experiments that his health broke down, 

 he became enfeebled, and was stricken with partial paralysis in 1868, 

 while he was in the midst of this important work. He had, however, 

 already found the cause and the mode of prevention, which consisted in 

 separating the healthy moths from those which were sick, carrying out 

 the true principle of isolation in infectious diseases, and thus he restored 

 the silk industry to France. He never fully recovered from the partial 

 paralysis which he suffered, so far as his body was concerned, but for 

 nearly thirty years his mind remained undimmed, and during these 

 thirty years he discovered the mode of curing those who are bitten 

 by mad dogs, until his Institute at Paris became the centre to which 

 alrlicted people resort from all parts of Europe for treatment. Another 

 important discovery which he made was the cause of fowl or chicken 



