STUDIES ON AVIAN H^MOPROTOZOA. 651 



such things as sugar-water, banana-juice, or mashed date. 

 And if they were not provided with something of this kind 

 they soon died off. 



I also obtained several batches of "wild" mosquitoes 

 (females), thinking these might at any rate bite. Indeed, 

 Prof. Minchiu, who sent me some from Norfolk, said they 

 were biting the horses in the open fields at the time. But 

 here again I had no better lack. In fact, the Culex seemed 

 to starve instead of feeding on the bird. I have kept batches 

 under observation without food,^ and seen their bodies gradu- 

 ally become attenuated, until, although placed for a couple of 

 nights consecutively with a bird, and without other food, by 

 the fourth or fifth day (since they last took food) many of 

 them would be dead. The mosquitoes were nearly always 

 placed with the bird in the late afternoon, and left with it all 

 night. Care was taken, of course, that they should be per- 

 fectly able to get to it and feed if they wished. Now 

 and again, also, I lield a tube containing a few hungry- 

 looking insects to the bird's body for a little time, displacing 

 the feathers so as to expose the skin ; and similarly with the 

 guinea-pig. I tried keeping the mosquitoes in a biological 

 incubator at a temperature of about 25° C. (77°-78° F.), for a 

 day or two before using them, but this did not make any 

 difference. Even small pieces of organs containing blood 

 from freshly killed rats remained untouched so far as I could 

 see. In short, all my efforts to induce Oulex to take blood 

 were unavailing. 



What is the probable explanation of this unwillingness 

 experienced of the insects to bite? Such a total failure in 

 this respect was quite unexpected. Taking into consideration 

 the results in this connection — fortunately more successful — 

 since gained at Rovigno, I think that there is probably more 

 than one reason for the above negative results. In the first 

 place, the question of temperature and moisture in the air is 

 very important. I found this to be the case at Rovigno. 



1 But not without water, a small dishful of which was always kejjt in 

 the cage. 



