TITE .MEANING AND USE ()[• TlfE COLOUR AND FoR.M ol' INSEC'I'S. 27 
markings of tlio caterpillar. In addition to this form of defence this 
caterpillar, if disturbed, can, as we have seen, suddenly assume a terrifying 
attitude ; while it has the still further power of ejecting a poisonous or 
nauseous liquid, which has a most repellent eflect on its foes. The 
greatest enemy that this caterpillar has is the ichneumon fly, and its 
method of attack is to plant itself, if possible, on the back of the cater- 
pillar, just behind the head: when once there the fate of the caterpillar is 
settled, as the ichneumon fly punctures the skin of this caterpillar and 
deposits her eggs there, and the larviP, which are hatched in a few days 
from those eggs, literally eat away the inside of the caterpillar until only 
the bare skin is left. Mr. Poulton records an interesting experiment he 
made and the combat he witnessed between these two insects, with the 
result that when the ichneumon fly got within range the caterpillar 
ejected its poisonous fluid and the ichneumon fly immediately collapsed. 
I have now come to the close of my lecture, and it is possible that 
some of you may ask in what way this subject is associated with horti- 
culture. If so, I may perhaps be allowed to remind you that the animal 
and vegetable kingdoms are so closely allied, so inseparably interwoven, 
the one with the other, that it is frequently difficult to know where the 
one begins and the other leaves off ; and, further, that the life of a 
gardener is a regular combat with insects, and that the study of such a 
subject stimulates observation. Moreover it gives him an intimate know- 
ledge of the many devices these insects have of evading his vigilance, 
and in that way, if in no other, it should prove of great use to him. 
Sir John Llewelyn, Bart., M.P., chairman of the meeting, in 
proposing a vote of thanks to the lecturer, said that he had listened to 
the lecture with the greatest interest, and thought at first sight it might 
appear to be a subject more nearly akin to entomology than to horticulture. 
Yet the two sciences were most intimately related, and whatever made 
the gardener think of the ways and habits of the insects, by which he was 
always surrounded, must be productive of great good, and would tend to 
the accumulation of a multitude of facts and observations connected with 
the life-history of garden friends and pests which must, in some way or 
other, be capable of being turned to good account. 
The Rev. Professor George Henslow^, V.M.H., in seconding the vote 
of thanks, also expressed himself as having been greatly interested in the 
subject treated by the lecturer. But he said he wanted to go a step 
further. The lecturer, for instance, had told them of cases in which 
animals, fishes, and insects changed their colours, respectively according 
to the colours of their immediate surroundings : the fact was indis- 
putable. Thus Sir Joseph D. Hooker had noticed a lizard in the 
Himalayas which was infested with ticks. The lizard's body was 
covered with scales which in some places were a dark brown and in others 
of a bright yellow. And he had noticed that a tick on a brown scale was 
brown-coloured, another on the bright yellow scales was also bright 
yellow ; but in the case of a tick l}ing upon two scales of different colours 
the part of the tick over the brown scale was brown, while the rest of its 
body over the yellow scales was bright yellow. The lecturer had cited 
the case of a plaice which was dark-coloured though lying on white sand, 
while all its fellow plaice were light-coloured ; and he had mentioned that 
