126 
F. M. CAMPBELL-ON INSTINCT. 
other day I was watching a spider (Tegenaria Guyonii , Guer.) lay 
its eggs, when it occurred to me to see what it would do if I 
removed them. This I did with a lifter, somewhat to the disturb¬ 
ance of the mother. After a few seconds she busily commenced 
to spin over the spot where she had just placed her eggs, and com¬ 
pleted her cocoon. It may truly he said that the habit of the 
species as to the form of the cocoon was so great that she might 
have been expected to proceed with it after she had deposited her 
eggs, even if she had missed them. There is, however, a physio¬ 
logical aspect to the act as well as a psychical. The maturity of 
the eggs may have been co-related with the greater activity in the 
collection of fluid by the spinning-glands ; and as is the case with 
the mammae of a vertebrate, the discharge of their contents may 
have been a necessity for the comfort of the creature. 
It is clear that we cannot shut out physiological conditions from 
the study of instinct, and while we admit a subtle relation between 
vegetative processes and adaptive action, we do not know its 
character, nor do we satisfy any enquiry as to development. We 
only assert the unity of Nature’s phenomena. 
Relation of Evolution to Instinct. 
I will now make a few remarks on the relation of evolution to 
Instinct, and will then proceed to the consideration of some other 
interesting points. It must be admitted that natural selection has 
largely influenced the development of those habits which are bene¬ 
ficial to a species, and therefore has much to do with the formation 
of instinct. The existence of any species shows that it possesses 
some advantage, humble though it be, which enables it to survive. 
The advantage may be its diminutive size, or its rapid reproduction, 
so that it only requires more simple conditions than others to 
support its life, and occupies as it were a corner in the world from 
which no other creature can quite displace it; but whatever the 
species may be, the effect of the struggle for existence favours the 
further development of the particular characteristic in which it 
already most excels, wherever advantage may acme from such 
further development, whether mental or structural. Man has so 
many occupations, and his cerebral complexities give rise to so 
many combinations, that inheritance has little chance of specialising 
beneficial habits. The wants of the lower animals are however 
few, and their occupations are those of obtaining food by direct 
means, of reproduction, and of protection. Any special structure 
or habit which more than others advances these ends has a greater 
opportunity of being developed. The tendency of natural selection 
is to improve, even to the neglect of others, that characteristic 
which brings the best result. Every animal has to work for its 
daily bread, and throughout the whole history of a species or variety 
it was obtained in the way which was the easiest under the cir¬ 
cumstances of the environment and the individual variation. 
Eurther, natural selection operates differently on each species. 
Thus, for instance, the varied and more elaborate webs of the spiders 
which build out of doors in the open, as compared with those 
spiders which are found in sheltered places, may be as much due 
