186 [August, 



years absence, lie returned to the islands, and his brother drew his 

 attention to the fact that Asclepias had been introduced during his 

 absence, and had already become a troublesome weed ; that his brother 

 had noticed that where the milk weed appeared, there also the Anosia 

 made its advent, a butterfly unknown until after the milk weed had 

 been introduced. We next find it in 1857 as far away as the Island of 

 Ponape (Ascension), one of the Caroline Islands in Micronesia, a dis- 

 tance of another two thousand miles or so from the Hawaiian Islands. 

 This fact we also owe to Dr. Gulick's personal testimony. He was for 

 some time a resident of Ponape, and the butterfly was first seen by him 

 in the year mentioned, not long after he had discovered several young 

 milk weeds, which had sprung up in earth in which various other 

 plants had been brought from the Hawaiian Islands in a Wardian 

 case. The plants were brought in a missionary vessel which sailed 

 from Honolulu, and on its way to Ponape touched only at Apaiang of 

 the Gilbert Islands and Ebon of the Marshall group, both low coral 

 atolls, and at Kusaie, which is of basaltic formation and richly clothed 

 with verdure, but where the butterfly did not then occur. It is 

 evidently impossible that in a voyage consisting in the whole of fifty- 

 four days, the insect in any stage or stages could have been transported 

 in the Wardian case itself, for it easily undergoes all its transformations 

 in warm regions in a month or five weeks at most. If the butterflies 

 were introduced at that time, as there is every reason to believe from 

 Dr. Gulick's accounts, there seems no other supposition possible than 

 that an impregnated female flew into the hold of the vessel while lading 

 at Honolulu, and was carried j^erforce to Ponape, or perhaps a pair of 

 butterflies. It would certainly be absurd to suppose that a gravid 

 female could have flown over the two or three thousand miles of ocean, 

 and in addition have appeared in Ascension Island almost simultane- 

 ously with a few plants of Asclepias. As the butterflies pass the 

 entire winter in hibernation, and then lay eggs in the spring, there is 

 nothing in any way surprising in Dr. Gulick's statements, unless it be 

 impossible for an impregnated female to live in enforced hibernation a 

 couple of months without laying, when it would be necessary to 

 suppose a pair to have been transported, which would of course be 

 more extraordinary. 



" Granting our explanation to be just, it is highly probable that 

 it was from this single ancestor, or pair, that the swarms, which have 

 already now spread over the entire South Seas, in many of which it is 

 the commonest butterfly known, have sprung. Our knowledge of the 



