94 SECTIONAL ADDRESSES. 
when the patterns are relatively simple. The distinguished mathematician, 
the late Prof. Study, of Bonn, who was deeply interested in mimicry, has 
shown, in two of his last papers, the impossibility of an explanation based 
upon chance resemblance, and I believe that the same conclusion will be 
reached by anyone who reads the chapter on Mimicry in Dr. R. A. Fisher’s 
recent work. 
The view has sometimes been held that mimetic resemblances are due 
to model and mimic independently passing through the same stage of 
evolution, either as a whole or in the mimetic features only; or, as 
Darwin once suggested, ‘ that the process probably commenced long ago 
between forms not widely dissimilar in colour’.6° I remember, at the 
Leeds Meeting in 1890, when Prof. Patrick Geddes suggested the former 
interpretation, that the late Lord Rayleigh remarked, “How would you 
apply your explanation to the resemblance of insects to bark, or twigs, or 
leaves ?’§! It is strange that this fatal objection did not occur to Darwin, 
for Bates himself in the great paper had written: ‘I believe . . . that 
the specific mimetic analogies exhibited in connexion with the Heliconde 
are adaptations—phenomena of precisely the same nature as those in 
which insects and other beings are assimilated in superficial appearance 
to the vegetable or inorganic substance on which, or amongst which, they 
live. The likeness of a Beetle or a Lizard to the bark of the tree on which 
it crawls cannot be explained as an identical result produced by a common 
cause acting on the tree and the animal.’® 
Before concluding, a few lines must be devoted to recent work on 
Sexual Selection, first briefly introduced as a factor in evolution by 
Darwin in the Joint Essay. Nothing would have interested and pleased 
him more than discoveries which, following the splendid pioneer work of 
Fritz Miller, have been made in the epigamic structures and behaviour of 
insects—the extensive observations on the scents of male butterflies, by 
Dixey and Longstaff, and on their scent-scales by Dixey ; the structure and 
use in courtship of the scent-brushes of male Danaine butterflies, by 
Eltringham, Lamborn, and Hale Carpenter; the extraordinary brushes 
protruded from the back of the head by the males of Hydroptila (Tricho- 
‘ptera), by M. E. Mosely and Eltringham ; the courtship of Empid flies, 
including the spinning of a cocoon as a wedding gift by the male Hilara, 
by Hamm and Eltringham ;* the fertilisation of orchids (Ophrys) by male 
bees (Andrena) which, emerging before the other sex, are attracted by 
female-like appearances, and probably scent, of the flowers, by Pouyanne, 
confirmed by M. J. Godfery, and by Mrs. Coleman, who has observed the 
there be found to resemble each other, although inhabiting opposite parts of the 
earth, and belonging to widely different families. Such analogies are accidental, 
and can have nothing at all to do with the evidently intentional system of resemblances, 
carried on from place to place, which I have discussed.’ 
60 Hssays on Evolution, p. 233 n. 
61 Proc. Ent. Soc. Lond., 1925-26, p. xev. 
& [bid., p. 508. 
88 Ent. Monthly Mag., 1913, p. 177; Proc. Roy. Soc., B., vol. cii., 1928, p. 327. 
All the other observations are recorded, with full references to earlier publications, 
in the Trans. or Proc. Ent. Soc. Lond. 
