351 



distributed over an area extending from Spain to Southern India, and from 

 Central Siberia to Abyssinia. — P. L. Sclater, Secretary. 



2. Linnean Society of London. 



6tli May, 1886. — Mr. D. Morris exhibited a number of living 

 beetles [Pyrophonis noctilucus) from the Island of Dominica. These had been 

 fed on sugar cane during the voyage to England. On the Meeting Room 

 being darkened the phosphorescent show of light emitted w^as very brilliant. 

 — Mr. Geo. J. Romanes read a communication on »Physiological selec- 

 tion ; an additional suggestion on the origin of species«. He stated that con- 

 sidered as a theory of the origin of species, natural selection encounters 

 three cardinal difficulties: 1st it cannot explain sterility between species, or 

 the primary specific distribution : 2nd it cannot explain many among the 

 secondary specific distinctions , or those trivial details of structure which, 

 while serving to distinguish one species from another, present no meaning 

 of an utilitarian kind : 3rd natural selection must always be so heavily han- 

 dicapped by the swamping efi'ects of intercrossing upon any new variation, 

 that unless such intercrossing is in some way prevented, we may reasonably 

 doubt whether natural selection alone could change one specie's into 

 another in more than a very small percentage of cases, although, when in- 

 tercrossing is prevented by the bar of sterility between species, natural se- 

 lection may afterwards produce genera, families, orders and classes. In view 

 of these considerations the author contended that the theory of natural 

 selection has been misnamed a theory of the origin of species. It is, in 

 truth, a theory of the origin of adaptive structures ; and, if unassisted by 

 any other principle, could not efi'ect the evolution of species. The only other 

 principle that could here assist natural selection would be one that might 

 mitigate the swamping efi'ects of intercrossing. This may be done by geo- 

 graphical barriers shutting ofi" a portion of a species from the rest, and on 

 allowing that portion to develop an independent course of varietal history 

 without intercrossing with the parent form. It may also be done by portions 

 of species migrating, changing habitual stations etc. But it may also be done 

 by what the author calls physiological selection, or in virtue of a variation 

 taking place in reproductive system in the direction of sterility (whether ab- 

 solute or partial] with the parent form, without impairment of fertility 

 within the varietal form. For instance, the season of fiowering or of pairing 

 may be either advanced or retarded in a portion of a species when all the 

 individuals in that portion (or new variety) would be absolutely sterile to- 

 wards the rest of the species, while completely fertile among themselves. 

 They would thus start on an independent course of variated history. Sundry 

 other causes (both extrinsic and intrinsic) may determine this particu- 

 lar variation in the reproductive system ; and wherever it does occur, it must 

 give rise to a new species to record the fact. The proof of its occurrence is 

 furnished both among our domesticated varieties and in nature. It explains 

 the sterility between species, the frequent inutility of other specific characte- 

 ristices, and entirely escapes the difficulty from intercrossing. It, therefore, 

 relieves the theory of natural selection from all the disabilities under which 

 it lies in consequence of having been improperly formed to pose as a theory 

 of the origin of species. — A paper, Descriptions of new species of Galeru- 

 cida by Mr. Joseph S. Bal y was thereafter read. — J. M urie. 



