INSTITUTE, PUSA, FOR 1919-20 103 



in spirit, adding fixed quantities of the repellents to the 

 solutions and exposing the mixture in equal quantities. 

 The following is an abridged statement of the average 

 number of flies that came to the repellents (which were tried 

 in various strengths) : Cinnamic aldehyde, ; Turpentine, 

 38-2; Camphor, 17-4; Napthaline, 22-6; Kerosine, 12-2; 

 Benzine, 26-8; Acetic acid, 19-2; Carbolic acid, 0; Oxalic 

 acid, 11-8; Hydrochloric acid, 10-8; Sulphuric acid, 3-4; 

 Mercuric chloride, 0; Soap (unscented), 12-8; Formalin, 

 28-6; Amyl acetate, 78; Control (Methyl eugenol only), 33-2. 

 Some chemical change seemed to have taken place in the case 

 of mercuric chloride. 



" (5) A further attempt was made to find out the role of 

 blood in ovulation in mosquitos. In my previous paper it 

 was stated that eggs were obtained with peptone and in 

 a few cases with milk, but the exceedingly small percentage 

 of successful experiments pointed to some accidental factor 

 being responsible for ovulation. The following were some 

 of the standpoints from which the problem was attacked : — 



(i) Leucocytes are present in the blood of both 

 vertebrates and invertebrates (which have been 

 found to be attacked by mosquitos). As 

 leucocytes are characterized by amseboid move- 

 ments and also in some other respects they 

 present a near parallel to Amoeba and Euglena, 

 it was considered probable that the larval habit 

 of eating Euglena in water was continued into 

 the adult habit of eating leucocytes (while 

 sucking blood) ; and if so, Euglena might take 

 the place of leucocytes even during the adult 

 stage. But out of the three experiments tried 

 with Euglena (sweetened with cane sugar), only 

 in one case were eggs laid by S. sugens. The 

 three experiments were continued for three 

 weeks. The result is, however, of interest inas- 

 much as this is the first instance in which eggs 

 were obtained with a mosquito other than 

 S. scutellaris without any meal of blood. 



