PROCEEDINGS OF THE CENTENARY MEETING. xix 



man to man by means of the Anopheles mosquito, that the yellow fever virus 

 can only be transmitted through the Stegomyia calopus, that the bubonic plague 

 may be carried from man to man or from rat to man by means of the rat 

 flea (Pulex cheopis), that the Trypanosoma gambiense of African sleeping sickness 

 can be communicated only by means of the tsetse-fly, that the organism causing 

 human filariasis is transmitted by the Culex fatigans and certain species of 

 Anopheles, and evidence is gradually accumulating that the bacterium of leprosy is 

 transmitted through the bed-bug, Cimex lectularius. A knowledge of the natural 

 history of these insects was absolutely essential for the scientific study of the dis- 

 eases with which they are so closely associated and public health work has only been 

 effective in eradicating the disorders in proportion to the efforts of the sanitarian 

 directed toward their destruction and for the protection of the individual. The 

 entomologist, the zoologist, and the bacteriologist are each required to contribute 

 their share in the research that means so much to public health and to mankind. 

 If much has already been accomplished, still greater are the fields open for 

 scientific investigation. 



With the lower forms of animal life parasitic to man and known to cause 

 disease, the connecting link, the intermediate host, the full life history are missing 

 in many instances where it would seem that the most fertile field for the scientist 

 has not yet been invaded. A very large province lies open for those who under- 

 take a careful study of the relation between the vermes and the human being. 

 Much indeed has been learned about parasites inhabiting the intestinal canal, 

 but the parasitologist has not yet concluded the final analysis of the life history 

 of many of these forms. 



The work of the Academy has been so distinctly pure science that the lay 

 public have not until recently appreciated the great practical relationship it has 

 to health and economics. The description of the various species, their life 

 history, their geographical range, have enabled those working in applied sciences 

 to conduct the already successful war against the enemies of man, of the lower 

 animals, and of plant life. 



Let it be remembered that in 1793 half the population of Philadelphia either 

 died from yellow fever, or voluntarily exiled themselves to escape from the 

 scourge, that all the southern tier of states were kept in a state of constant 

 terror every summer for fear of its invasion, causing a loss of millions to the 

 commerce of the country, and then recall the fact that through entomological 

 and medical cooperation this disease was practically eliminated from Cuba, its 

 breeding place for ages, and that in 1905, a violent epidemic of the same plague 

 was actually checked in New Orleans by the application of the knowledge gleaned 

 by the medical department of our army in the more southern field. 



That mysterious blight to human life and energy known as malaria, to which, 

 as much as to the fire and sword of northern barbarians Greece and Rome owed 

 their downfall, has been traced to its entomological source so that these two 

 devastating diseases have ceased to be a menace to civilized communities, 



