August 8, 1919] 



SCIENCE 



129 



7. Does this movement of the organism 

 suggest whether the transmission is by in- 

 oculation or does it suggest that the organism 

 will pass out of the body in some of the 

 excreta ? 



8. Can the organism be demonstrated in the 

 mouth parts of the insect at the time of 

 feeding ? 



9. Can the organism be found in any of the 

 excretions of the insect? 



10. How long is it before the organism 

 reaches the mouth or the rectum? 



11. What is the earliest date at which it can 

 be found in the feces? 



12. What is the earliest date at which in- 

 fectivity of the host can be obtained by the 

 sucking of the blood? 



12. What is the earliest date at which in- 

 fectivity can be obtained by scratching in of 

 feces or portions of the insects? 



14. Can infection be obtained by either 

 natural or artificial inoculation without dem- 

 onstration of the organism? 



15. Is the infective organism or virus filter- 

 able? 



16. Can the virus or organism be trans- 

 mitted hereditarily? 



17. At what stage of development in the 

 second generation does hereditary transmis- 

 sion become possible? 



18. Can the organism be taken up by the im- 

 mature stages, feeding in infected excreta? 



19. Can the organism be taken up by im- 

 mature stages of an invertebrate feeding on 

 the host? 



20. How long can the immature forms of 

 the invertebrate, infected by whatsoever man- 

 ner, retain the organism in their system? 



21. Does it stay during metamorphosis? 



22. Does it undergo any changes preceding 

 or following metamorphosis? 



23. At what stage in the metamorphosis 

 does the insect begin to be infective after 

 taking up such organisms? 



24. How long caa the insect remain in- 

 fected? 



Vlir. HOW SHOULD EXPERIMENTAL INSECTS BE 

 HANDLED ? 



A large proportion of the failures in studies 



of insect transmission in the past have arisen 

 from improper handling of the insects. The 

 breeding and handling of the insects is an 

 art in itself, just as is the culturing of bacteria 

 or protozoa. In fact there are more diverse 

 requirements for handling insects of different 

 species than can be found elsewhere in the 

 animal kingdom. 



1. What must he known about the insect 

 before beginning transmission experiments? — 

 The normal conditions of life of the insect 

 must be ascertained: its reactions to heat and 

 cold, moisture and dryness, disturbance, color, 

 light, odor; its food, and the proper condition 

 thereof; its methods of reproduction, and what 

 food is necessary for reproduction; if soil 

 should be provided, and what conditions it 

 should be in; if water should be provided, and 

 whether this water should be alkaline or acid, 

 clear or containing foreign matter, and in 

 such case what type of foreign matter; 

 whether the water should be still or in motion, 

 warm, moderate or cold. 



2. What type of breeding cage should be 

 used? — A breeding cage must be used which 

 wiU most nearly enable the experimenter to 

 keep the insects under control and yet repro- 

 duce essential conditions for maintaining 

 reproduction. Much of this information is 

 normal healthy life of the insects and normal 

 available in entomological literature. Many 

 insects probably involved in disease trans- 

 mission have not been properly studied and 

 breeding technique is yet to be worked out. 



3. Water is necessary in some form in prac- 

 tically all insect breeding. — There are more 

 failures to properly breed insects traceable to 

 improper humidity, or to the lack of moisture 

 in the proper form for the insects to drink. 

 Much detailed observation may be necessary 

 to obtain this important information in the 

 case of many insects. 



4. There is a combination of temperature 

 and humidity most favorable for life, for each 

 species, and differijig from, one species to an- 

 other. 



4. The food of an insect must be in a par- 

 ticular condition in order to obtain normal 

 breeding. It may require a certain degree of 



