( iep.-) 
compound-eye must be very different from that of the vertebrate 
eye; that itis inferior in perception of plane surfaces, but 
superior in distinguishing objects in the third dimension of 
space, that is, depth. 
Patten is the last, but by no means the least, of the 
investigators of the insect-eye: his papers are chiefly 
anatomical, and are more especially directed to questions 
connected with the development and common origin of 
different invertebrate eyes; but he has a chapter on the 
function of the compound-eye of the insect, chiefly remark- 
able from its going a long way towards recognising the 
extreme difficulty of settling this: his special contribution to 
the anatomy of the organ I shall briefly mention further on. 
Here I will take the opportunity of mentioning that there 
is on record a very curious observation relating to the vision 
of insects, though it has apparently escaped the attention of 
recent writers. It is an article by Mr. Spence,—in fact, the 
very first memoir published by our Society,—-and forms 
Article I. of the first volume of the first series of our 
‘ Transactions.’ 
Lubbock, whose opinion is of great value, because of his 
skill and experience as an observer of the habits of insects, 
says, in his recently-published book, ‘‘ We know as yet very 
little with reference to the actual power of vision possessed 
by insects.” 
From the above I think we may fairly conclude that it is 
quite uncertain what insects do see, or whether they see at 
all, if we use the word seeing in association with the idea of 
our own plane-picture seeing. 
Here, so far as my chief object to-night is concerned, 
I might leave the question, for I hope I have made it clear 
that we are quite ignorant on the subject of the sight of 
insects—the most important of their senses—and have, in 
fact, no knowledge whatever such as we ought to possess 
previously to coming to any general conclusions of importance 
about their habits, so far as these are affected by sight. I 
think it probable that the sense of sight in insects is, in so 
far as the eye is concerned, a more complex matter than it is 
in the Vertebrata: such ocular perceptions as are requisite 
for the orientation of the creature must be sought in the 
