DARWIN AND BERGSON ON EVOLUTION 



to a manifestation of " Creative Evolution " — the gradual or sudden 

 expression of forces locked up within the organism (4). The fact of 

 female Mimicry is of course a serious difficulty encountered by the 

 last hypothesis, but any further discussion of these two rival inter- 

 pretations is better postponed until after the consideration of Acrcea 

 alciope and its Models in Uganda, at the opposite or eastern side of 

 their range. 



Our detailed knowledge of these forms in the neighbourhood of 

 Entebbe is almost entirely due to Mr. C. A. Wiggins, D.P.M.O., of 

 the Uganda Protectorate. The constant pressure of official duties 

 has prevented Mr. Wiggins from breeding the insects, but by 

 employing natives to collect at short intervals, by collecting himself, 

 whenever the opportunity offered, and, above all, by keeping the 

 collections distinct and carefully labelled, he has thrown a flood of 

 new light upon the numerical relations of Models and Mimics, at 

 different seasons and in different years. A part of his results, 

 including A. alciope and its Models, obtained between May 23rd 

 and August 31st, 1909, was communicated to the first International 

 Entomological Congress at Brussels, in August, 1910, and is published 

 in the Report. During the past year Mr. Wiggins took the oppor- 

 tunity afforded by his leave to study the whole of the vast mass of 

 material presented by him to the Hope Collection at Oxford. Work- 

 ing together we have tabulated and expect soon to publish an account 

 of all the mimetic associations captured between August 31st, 1909, 

 and February, 1911. The figures on the present occasion will be 

 quoted from the Brussels paper, but it may be said that the more 

 extended study in every way confirms the earlier conclusions as to 

 the relationship between Model and Mimic. 



Planema alcinoe, the western Model, also occurs at Entebbe, but 

 it is unaccompanied by any of the western species with a fulvous- 

 marked pattern similar to that of its male. It is not very common, 

 thirty males and eleven females being taken in thirty days' collecting 

 between May 23rd and August 31st, 1909. On the other hand, 

 thirty-five males and fifty- two females of Acrcea alciope were cap- 

 tured in thirty-four days between the same dates. It is therefore, 

 not surprising to find that, in the eastern part of its range, the 

 female alciope is no longer a Mimic of PL alcinoe. It may be of 

 interest to those who believe in the paramount importance of climate, 



GO 



