380 
whether the same applies to “wild” individuals. At any rate, the paired 
masses of eggs develope to their full size, ready for fertilization, upon one 
meal of blood. This summer, I have succeeded in obtaining fertile egg- 
rafts and larvae from bred-out males and females. I have a strong idea 
that a second meal of blood is taken normally before the fertile eggs 
are laid, the eggs being laid, in fact, immediately after the meal, which 
has perhaps induced the oviposition. I have found this to be the case 
in at least two instances; and, on the other hand, I have noticed that a 
gravid female, which has not fed again, will occasionally lay her 
eggs, but these have not been fertilized. A point to which attention 
must be drawn is that, as a result of a meal of blood, the eggs always 
do grow, apparently Ma their full size. 
Now, in the hibernating female mosquitoes, the eggs apparent in 
the ovarial tubes are quite young (the females were, of course, fertilized). 
There are, it would seem, two alternative explanations. (a.) These in- 
dividuals had never taken blood. If this were the case, it is obvious that 
the “Crithidiae” could not have developed directly from a blood-Try- 
panosome. (b.) After one or more meals of blood, they had developed 
and laid a batch of eggs, and the young eggs present represented asuc- 
ceeding batch. In none of the individuals I dissected could I obtain any 
definite indication which of the two interpretations was the correct one. 
But within the last few weeks, Major Perry, I. M.S., who in my ab- 
sence was examining some females which had entered upon hibernation 
this (present) autumn, in the same cellar, found in one case a single, 
full-sized egg, in addition to the customary small ones; 7. e., one of the 
preceding batch which had been left behind when the rest were laid. 
This shews at any rate that the second alternative noted above does 
happen; in other words, that these hibernating females may have taken 
blood. And that is as far as I have been able to carry the problem up 
to the present. 
From the above considerations, it still appears to me quite likely 
that * Crithidia” fasciculata is connected with a Trypanosome. Never- 
theless, in view of the occurrence of cysts which are paobably destined 
to infect the larvae, it is equally possible that this parasite is solely an 
Insectan Flagellate, that is, one restricted to the mosquito, which has 
become adapted to the sanguivorous habit of the female; I may recall 
that I expressly indicated the possible occurrence of such forms some 
years ago, though this suggestion of mine has been wilfully overlooked 
by some of my critics’. 
Up to the present, there is no instance which is definitely established, 
We Vide Lankester’s treatise on Zoology, pt. 1. fasc. 1. Art: Haemoflagellates. 
p. 244. 
