9 o 'WHAT IS A SPECIES?' 



of the naturalist. Just as Harvard has her main Obser- 

 vatory at the University, but also maintains an outlying 

 institution in the Peruvian Andes, where certain kinds of 

 research, unsuited to New England, can be carried on 

 under the most favourable conditions, so our chief 

 museums should be provided with the means of es- 

 tablishing temporary stations in the most favourable 

 parts of the tropics. When I say temporary, I do not 

 refer to the means, but to the position of the station, 

 which should be freely movable in response to the call 

 of important problems as they present themselves for 

 solution in other localities. 



Another urgent reason for the establishment of bio- 

 logical stations is forced upon us by the inadequacy 

 of Diagnosis for the separation of very variable species, 

 such as many of the African Acraeinae. I cordially 

 agree with the view often expressed to me by my friend 

 Mr. F. A. Heron, of the British Museum of Natural 

 History, that we shall never reach a secure foundation 

 until epigonic series have been obtained on a large 

 scale. To achieve this end a temporary station would 

 be required. In this way our museums could receive, 

 and should keep for permanent study, the whole of the 

 offspring reared from the eggs of a single parent. If 

 several species were thus represented by one or more 

 large epigonic series, we should know what to expect 

 and what to allow for ; and Diagnosis in general would 

 gain the most helpful guidance. 



Asyngamy as a consequence of certain Adaptations for 

 Cross-Fertilization. 



Asyngamy, as regards particular lines of union, has 

 also been incidentally brought about by certain adapta- 

 tions for cross-fertilization in plants, and such Asyngamy 

 has in some cases persisted long enough to have led to 

 sterility in greater or less degree. Of all Darwin's work, 

 that upon the fertilization of heterostyled plants threw 

 most light, he considered, upon sterility between species. 

 As Francis Darwin has stated, ' He found that a wonder- 



