MALARIA EXPEDITION TO NIGERIA 245 
(2) That blood is necessary for the development of ova. 
(3) That the blood must be available regularly — at least every two days — 
for the development of ova. 
(4) That the power of propagation of the species is acquired in a very 
short time after the production of the imago, and is extremely 
vigorous during the whole life of the insect if feeds of blood 
are available. 
(5) That one act of fertilisation by the male suffices for a considerable 
period of ova production. 
(6) That even in spite of fertilisation not having occurred, ova develop 
if regular feeds of blood are procurable, and may be deposited 
on water. 
(7) That unfertilised, fully-developed ova may be carried by the female 
for a considerable period (four weeks in our experiments). 
R 
