MIMICRY, MUTATION AND MENDELISM 



larvae or pupae from Gazaland in south-east Rhodesia and pairing 

 the resulting males with Natal females. The hippocoon form is far 

 more dominant in the former locality than cenea in Natal, and it 

 may be safely assumed that the vast majority of the males would 

 bear the tendencies of hippocoon alone. If the proportions of the 

 female forms observed in any locality are reflected with tolerable 

 accuracy in the families reared from females of that locality — and 

 this is certainly true in Natal and in the Lagos district of West 

 Africa — we may feel confident that nine out of ten hippocoon females 

 from Chirinda in south-east Rhodesia would yield hippocoon females 

 and no others. The experiment has not yet been attempted at 

 Chirinda, but it has been tried in the Lagos district, where the 

 western form of hippocoon is at least equally dominant. I here 

 predicted that no females but hippocoon would be bred from the 

 great majority of parents of this form. My kind friend, Mr. W. A. 

 Lamborn, has now bred six families for me. The female offspring 

 of all six are without exception hippocoon. 



The explanation of the relative proportions of the female forms in 

 different parts of Africa is to be found in the prevalent local Danaine 

 butterflies and in the presence or absence of a single Acraeine. In 

 Natal, the two species of Amauris (Figs. 4 and 5 on Plate I.) are by 

 far the most abundant Danaines, while A. dominicanus (Fig. 2) is 

 generally rare, and often not to be seen at all. D. chrysippus 

 (Fig. 3) is always common, but it frequents the more open woodland 

 spaces, while P. dardanus prefers the dense forest ; and model and 

 mimic only mingle freely where the two types of country pass into 

 each other. Probably on this account the trophonius form, although 

 occurring wherever dardanus exists in Africa, is always relatively 

 rare, while its ubiquitous model is common throughout the Ethiopian 

 Region. As we pass westward into Cape Colony the proportions of 

 the female forms remain much the same, except that hippocoon is 

 even rarer than in Natal, while its model, A. dominicanus, is alto- 

 gether unknown. Passing northward along the east coast, the 

 striking feature is the rapid increase and predominance of hippocoon 

 and the relative rarity of cenea as well as trophonius. This change 

 corresponds with the rise in importance of A. dominicanus. Even 

 where echeria and its ally are far more abundant than dominicanus, 

 if the latter be at all common, hippocoon will be abundant and cenea 



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