exl Proceedings of the Asiatic Society of Bengal. [N.S., XV, 
But an insect has often to confine itself to a particular 
diet with a strictness that no human doctor would ever insist 
a 
try something else which does not ee w the proper recognition- 
Some years ago I compared insects in general to human 
beings in the condition commonly known as a hypnotic trance. 
A person in this condition may follow out with the utmost 
concentration a tog set of instructions, but be almost ob- 
livious of anyt which does not come within the prescribed 
circle of ideas. ak o it seems to be with insects; there are 
certain instructions, so to a as to how to recognize food, 
where to lay eggs, and so on, and they are followed. The 
more narrowly precise sad definite the instructions (i.e. the 
more specialized the insect and the deeper its ‘‘ trance’’) the 
greater the concentration — which they are obeyed and the 
greater the pager’ of erro 
defining effective sen Ne we must then take recognition 
as a definite factor. It is necessary for an insect to recognize 
its food and also to be in sufficiently close bodily contact with 
it. 
ut “an insect”? may be all sorts of different things at 
different periods of its life; the caterpillar, for instance, was 
hatched from a harmless egg -and will turn into an equally harm- 
less sb ae: and then a — charming butterfly, all 
quite incapable of damaging plants. No one is afraid of a 
plague-f -flea’s oes: or of an Anopheline larva so long as it re- 
mains a larva. That is not the time at which it is dangerous. 
We see then that if an insect is to make effective contact 
with its victim it must fulfill three conditions: it must be in 
bot y and “psychological”? or sensory contact with it, 
and must also be in what we might call “ temporal” contact ; 
ie. at the right time, the right period of its own and the 
sg s development. 
now, having got these three essential factors, bodily 
cacaiie: sensory contact, and time-contact, it seems to me that 
host ; ~~ although this model must, owing to our ignorance 
of many important matters, be very inc omplete, it will at least 
have the merit of being something a something one can 
look at and think about and criticis 
Let us take a simple case, itthaok say a ‘‘ hardy annual,” 
and consider the extent of its mobility, its bodily range of 
motion in — We assume that the only time it ex 
hibi iable ie eatd is at the season when it exp 
its tnhge gy scattering its , and for the rest of its life its 
