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 using 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-known 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 ResparcH IN THE LIFE-HISTORY 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 larve) 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, e.g., with a 
stain or powder, and to trap them again. 
3. Habits, especially of the male, and conditions of fertilisation. 
4. Kffect 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 Huropean 
bungalows ? 
8. Habits in the dry season. 
9. When does egg-laying of Anophelines 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 ? 
