XXXI1X 
creatures, the protection gained was no less clear; and this was termed mimicry, 
because one insect was, as it were, dressed to imitate another. Mr. Bates first showed 
| how extensively this prevailed in nature, especially among the Lepidoptera, and 
argued that if the imitated forms had any special immunity from attack, the species 
of other groups which resembled them would to some extent be free from attack also, 
and would thus gain an advantage in the struggle for existence. He then shewed 
that the forms imitated always belonged to dominant groups, or those excessively 
abundant in species and individuals, and therefore presumptively free from the attacks 
of those insect-enemies that kept down the numbers and threatened the extinction of 
other species; and that in the case of the Danaide and Heliconiide (the groups most 
frequently imitated all over the world), the protection was probably the powerful odour 
they emitted. The theory of natural selection, or the preservation of useful variations, 
was shown to be fully capable of explaining these facts, and it bore the test of a true 
theory by also explaining other anomalies as they arose. A species of Diadema was 
then exhibited, in which the female was glossed with blue, while ihe male was dull 
brown, thus reversing the usual sexual characters of the genus; and it was observed 
that the male in insects was usually more active, the female more sluggish ; the male 
gaily coloured, the female dull; and these facts were connected by the consideration 
that the female, having to carry a heavy load of ova, and to deposit them in places 
favourable for their development, required protection for a much longer period than 
the male, whose duty of fecundation was very speedily performed. Thus dull colours 
were useful to female insects, since it rendered them less conspicuous. It followed 
that any other kind of protection would be also more necessary for the female than for 
the male, and, to show that this really was so, a male specimen of the well-known 
leaf-insect (Phyllium, sp.) was exhibited, having none of that wonderful protective 
resemblance to a leaf which characterises the female. So in the well-known case of 
Diadema Bolina, the male was a richly-coloured blue, white, and black insect, while the 
female was orange-brown, quite differently marked, and resembled most minutely 
Danais Chrysippus, which had a range nearly coincident with it. It was suggested 
that the explanation of the anomalous insect which was the origin of these remarks 
was, that the female, by acquiring the metallic-blue gloss, was made closely to resemble 
the common Euplewa Midamus which inhabited the same localities; it thus gained an 
advantage in being mistaken for a species which insectivorous birds did not attack. 
Mr. Bates was of opinion that the individual of Pieris Pyrrha described by Professor 
Westwood presented simply an instance of unequal hermaphroditism, three-fourths 
male and one-fourth female. As such it was a mere monstrosity, and had no bearing 
whatever on the question of the origin of species; the Darwinian theory dealt only 
with variations that were propagated, and not with monstrosities, the peculiarities of 
which were not transmitted to their descendants. With regard to those cases where 
the female sex of a species alone was found to mimic species of other families, the 
male remaining true to the normal type of its group, he thought it was absolutely 
necessary that an entomologist should have had opportunities of observing the habits 
of the species before drawing conclusions concerning them. In all such cases he had 
found that the females had a different mode of life from the males, In Pieris Pyrrha 
and other allied species the females were confined to the shades of the forest, where 
they flew near the ground, and were slow in their movements; whilst the males spent 
the hours of sunlight flying about open places, in company with the males of a great 
