8 J. W. W. STEPHENS — METHODS FOR DETECTING SPOROZOITS, &C. 



6. Penetration of red cells by sporozoits. — Using a mixture of finger-blood 

 and sporozoits from the salivary gland, Stephens and Christophers were unable 

 to observe penetration of the red cell by the sporozoits, but the latter appeared 

 to change into rings. Nor did Schaudinn, making the same experiment, succeed, 

 but on usiug sporozoits taken from a large oocyst in the stomach he was success- 

 ful. These experiments are worthy of repetition and an explanation should be 

 sought for the difference in the behaviour of the sporozoits from the two sources, 

 if the facts are correct. 



7. Properties of the salivary secretion. — As far as I am aware, nobody has 

 yet repeated Schaudinn's observations. He states that the salivary gland rubbed 

 into an abrasion does not produce the irritation of a mosquito bite, but that on 

 the contrary if the oesophageal diverticula be rubbed in, the well-laiown itching 

 effects are experienced, which he attributes to the enzymes produced by low 

 bacterial forms in the diverticula. Any fact established about mosquitos is of 

 value for we never know to what practical purpose such knowledge may not be 

 turned. 



Suggested lines of Research in the Life-histoby of Adult 

 Mosquitos. 



Finally, in addition to the problems we have indicated as awaiting research 

 dependent mainly on microscopical methods, there are numerous points concerning 

 adult mosquitos (apart from larvre) on which further light is required, problems 

 which are to be solved rather in the field than in the laboratory. Such for 

 example are : 



1. Length of life. 



2. Distance of flight. It might be possible to mark mosquitos, c.c/., with a 

 stain or powder, and to trap them again. 



3. Habits, especially of the male, and conditions of fertilisation. 



4. Eft'ect of jungle, bush, bamboo-thickets, and banana-clumps as screens. Is 

 it advisable to clear all jungle indiscriminately, without regard to its screening 

 function ? 



5. What are the natural enemies of adult Anophelines ? 



6. Is it possible to discover any plant or substance that will entirely repel 

 mosquitos ? or on the contrary that will irresistibly attract them ? 



7. What is the best form of mosquito trap and to what extent can mosquitos 

 be diminished by persistent trapping every night in native huts or European 

 bungalows ? 



8. Habits in the dry season. 



9. When does egg-hiying of Anojjhelines take place in nature ? Has it any 

 relationship to food ? What determines selection of any particular water ? 



10. How often does an Anopheline leave a native hut or bungalow ? 



