35 



or else upon solid bodies not too far removed from the level of the water, 

 so that a moderate elevation of that level will allow the water to cover 

 them. My explanation about the need of several bites and feeds of 

 blood before the C. mosquito is able to lay all its ova, may be purely hypo- 

 thical : it is nevertheless a fact that the females of that species are always 

 ready to bite a second time after they have digested all the blood which 

 had been sucked at a previous bite. A female C. mosquito, caught (in 

 Havana J in January of the present year, had bitten 12 times and laid 

 eggs three times in the course of the 31 days which it lived ; its death 

 having occurred in New York where it was exposed to temperature below 

 the freezing point. 



With the captive females of the C. Cubensis (C. Pungens), I have 

 never been abb- to obtain a second bite, whether it had or had not laid 

 its ova. Possibly, however, when at large they may need 1" 



times before laying; for I have i asionally seen them come to bite my 



hand, with some blood already in their stomach. This I have attributed to a 

 previous bite which had been interrupted before the insect had been able 

 to draw its full allowance of blood. 



Evidently, from the point of vif-w which I am considering, the Cu- 

 lex mosquito is admirably adapted to convey from one person to anoth- 

 er a disease which happens to be transmissible through the blood; since 

 it has repeated opportunities of sucking blood from different sources, 

 and also of infecting different persons; so that the probabilities that its 

 bite may unite all the conditions required for the transmission will there- 

 by be greatly increased. On the other hand, inasmuch as the ' 

 bensis absorbs a larger quantity of the infectious blood at each feed, its 

 mouth-parts may retain a Larger amount of virus, and perhaps produce 

 a graver inoculation when it happens to attack a non-immune a few 

 moments after having bitten the patient, its first bite having been in- 

 terrumped. In that case, a graver infection might result but the chances 

 of its occurring would be much less. 



In order to understand the special facilities which the bite of the C. 

 mosquito affords for the inoculation of any infectious particles which 

 should be contained in the blood, it is necessary to have some idea of the 

 disposition and structure of the apparatus used by the female mosquito 

 in its operation of stinging and of sucking blood. 



What is seen of the proboscis, under ordinary circumstances is the 

 sheath, which represents a modified nether lip. It arises from a pedicle 

 attached to the base of the head, below the other mouthparts. It is slit 

 along its upper border as far as the terminal, conical button seen at its 

 free end, and which, I believe, is formed by two labial palps. From 

 the extremety of this button the other pieces constituting the sting are 

 protruded (in the act of stinging). The sheath of the C. mosquito, to 



