ARTHROPODA 571 



In conclusion I must mention the 



INSECTS 



which are parasitic in man, and I should first like to consider the role which 

 they play in the transmission of infectious diseases. The reports concerning 

 this are scanty and widely scattered. 



From the interesting investigations of Futall it appears that it is only 

 rarely that anthrax, chicken cholera and mouse septicemia are transmitted by 

 bed-bugs and fleas, probably because the insects which absorb the microorgan- 

 isms with their sting, soon rid themselves of them. It cannot, however, be 

 denied that by crushing the sucking animals which contain these microorgan- 

 isms in their blood, and by scratching at the point of the bite, these germs may 

 be conveyed to man. But it must be remembered that the infectious germs 

 which are present in the dejecta of bed-bugs and fleas lose their toxic proper- 

 ties very rapidly. This is especially noticeable in fleas. 



Plague bacilli, transmitted to bed-bugs and fleas, appear to die in the 

 intestinal canal of these insects. The danger lies in the fact that if any one 

 crushes an insect thus infected, and the bite is then rubbed or scratched, the 

 bacilli may be transmitted. It is certain from the experiments or Simmond 

 that flies which have fed upon the dejecta or the bodies of cholera patients take 

 up cholera germs, and transmit them to food. Eelapsing fever spirilli taken 

 into the intestine of "bed-bugs appear to die with relative rapidity. The imme- 

 diate inoculation of apes with bed-bugs that have sucked themselves full and 

 have been crushed, has been followed by positive results. Typhoid bacilli may 

 apparently be carried by flies. It has been further proven that flies may take 

 tubercle bacilli into the intestinal tract. The bacilli have been found in the 

 dejecta (fly specks) upon walls, in closets, and on doors. It is not unlikely 

 that in regions where leprosy exists it is transmitted by means of sarcoptes. 

 The bubo disease, Egyptian ophthalmia, and conjunctivitis blennorrhoica may 

 be transmitted by flies. Favus and impetigo are said to be transmitted by lice. 

 That infectious diseases are transmitted to man by means of the Ixodes is more 

 than doubtful. The role played by the Ixodes bovis, Riley, 1869, or the booph- 

 ilus bovis, Curtis, 1890, and by the tsetse fly in Texas fever, the tsetse fly 

 disease, has not come within the range of our observation. 



Of the parasitic insects I shall only refer briefly to the head louse (pedicu- 

 lus capitis, de Geer). This parasite is distributed over the entire world. It 

 generally lives upon the hairy scalp, but in cases of great uncleanliness also 

 infects other parts of the body. The ova of the head louse are rarely found 

 in the cilia. From the excrement of the lice which is conveyed to the con- 

 junctival sac by the hands, conjunctivitis and blepharitis may apparently be 

 produced. In cases of stubborn head eczema, especially in children, the pres- 

 ence of lice should invariably be looked for. It is known that plica polonica 

 usually develops from a preceding pediculosis capitis with accompanying 

 eczema. The plica polonica (Polish plait) must be removed with the scissors. 

 To exterminate lice, washings with vinegar, petroleum, or corrosive sublimate 

 (1-1,000) and combing the hair by means of a fine comb are advisable. The 

 scalp should then be painted twice daily with Ziett-Lassar zinnober salve: 



