29 
What we want to have observed, then, are the fluctuations in the 
numbers of a species from year to year. We should expect to And any 
excess of numbers would be closely followed by a rather greater fall. 
A speculation of this sort applies, of course, to any living being, 
and it h interesting to reflect that the beginning of some such cycle as 
we have been considering, has been progressing amongst the nations 
of Western Europe for the last century or two. The pressure of selec¬ 
tion has been immensely diminished by two great discoveries—the 
industrial use of coal, and vast regions of great mineral and agricul¬ 
tural wealth thrown open for occupation. How it will be with us 
when coal is exhausted and these new territories are filled up, and 
selection again presses with its old force, is still, fortunately for us, a 
long way in the future, but it will inevitably come. Already we are 
told, but are perhaps too clos9 to the facts to observe them accurately, 
that there is an undue increase of undesirable (i.e., unselected) 
individuals, especially at the extremes of the social scale. 
WHICH IS OK GREATER IMPORTANCE TO THE RHOPALOCERA— 
THE UPPER OR UNDERSIDES OF THE WINGS? 
(Read April 6th, 1909, by Du. G. G. C. HODGSON.) 
In attempting to suggest some lines for the discussion of the 
question proposed for to-night, one has probably been unusually un¬ 
successful in the matter of confining the attention to a definite point: 
the point (defined as having no magnitude and no parts) on observa¬ 
tion assuming the appearance of a gigantic radiating organism of 
almost unlimited dimensions. Some tentacles are buried in such 
questions as those of sexual selection, and the inheritance of acquired 
characteristics—two possibly of the most debateable topics of the times. 
Other tentacles are wound among the evolution of butterflies ; their 
sexual and their seasonal dimorphism or polymorphism ; the effects of 
surroundings (climatic or otherwise); mimicry; and when further 
other tentacles are found entangled in such a study as their enemies, 
nature, habits, and predilections, where are our guides with the 
tentacles? Our authorities on these topics, where? 
Probably in this connection, more than in any other, we are “ up a 
tree,” though, unfortunately, metaphorically only. For physically the 
position might have a practical and useful result. In that position 
valuable observations might be carried out, as it seems a scarcely 
avoidable assumption that, with regard to the enemies of butterflies, 
no other of their foes has just the range of space, to which our vision 
(unless through specially adopted attitudes) is absolutely limited, viz., 
from three to six feet above the solid ground. So that it would 
seem fair to assume that, so far as we have succeeded in our estima¬ 
tion, any realisation of harmony with their surroundings is not under - 
estimated by us in the matter of butterflies’ undersides, but that, con¬ 
ducting ourselves in an average human fashion, we are heavily 
handicapped in this matter—are perhaps fairly incompetent to judge. 
xix. 
