SCIENCE-GOSSIP. 



313 



into two or more. Some form of isolation is 

 required to do this. The second great difficulty is 

 the contrast between the fertility among artificial 

 varieties, and the sterility between natural species. 

 It is claimed that these difficulties are done away 

 with on the new view. 



The thing, then, which Dr. Romanes has most 

 clearly proved is that divergent evolution is a 

 logical impossibility without some form of isola- 

 tion. This had already been done by many critics 

 of Darwinism, and must indeed be evident to all 

 thoughtful minds. It is doubtless the leeling of 

 this insufficiency which has led to the many 

 amendments to Darwinism which have from time 

 to time appeared. When, however, we come to 

 Dr. Romanes' method of supplementing natural 

 selection, we cannot follow him so easily. The 

 swamping effects of inter-crossing are convincingly 

 dwelt on ; but, one asks, does not this swamping 

 tell equally against the new theory ? For the 

 cross-infertility is but a variation beginning in a 

 small way, and as such, amenable to the laws of 

 variation, viz., in the presence of free inter-crossing 

 to be absorbed. As far as one can see, there is 

 absolutely nothing to prevent free intercrossing. 

 Thus, while Dr. Romanes has doubtless made a 

 formidable breach in the walls of the theory of 

 natural selection as usually held, he has not, in 

 my judgment, succeeded in repairing the same by 

 the props of physiological selection which he 

 has inserted. He has, however, defended his 

 position in his usual brilliant style against all 

 comers. It would be Alhunasius contra miiiiduni if 

 it were not for his fidus Achates, Mr. Gulick, for 

 no other evolutionist accepts his views. And 



having hit out with force and precision all 

 round, we have at the close of the book, as 

 is fitting, the handshake of the opponents. 

 Readers are requested to note how great, in 

 spite of the noise of conflict, is the solid 

 agreement of evolutionists on all really great 

 questions. Whether the reader will be con- 

 vinced of this solid underlying agreement in 

 spite of apparent discord, seeing that each 

 owner of a theory clearly proves that to be 

 impossible which the other demands as essential, 

 will be a matter of individual taste and bias. 

 When, for example, Weismann proves as rigidly 

 as scientific proposition has ever been proved, that 

 there is no transmission of acquired characters, 

 and considers that natural selection alone has 

 done all the work in the evolution of species, while 

 Romanes deems it absolutely necessary that it 

 should be supplemented not only by such trans- 

 mission, but by physiological selection as well ; 

 and the Neo-Larmarckians in America deem 

 necessary more transmission of acquired characters 

 than even Darwin assumed ; and Romanes proves 

 conclusively that without physiological selection, 

 or other form of isolation, there can be no diver- 

 gence of species, while Wallace and others contend 

 that there is no such thing as physiological selec- 

 tion ; when certain Darwinians, as did Darwin 

 himself, consider that sexual selection is an 

 essential factor in the making of species, while 

 Wallace and others have discarded it and shown 

 it to be absurd ; there surely seems room for 

 difference of opinion as to the solidity of the 

 agreement. 



Jesmond, N eu-castle-on-Tyitc. 



FIGHTING AN INSECT. 



TT was not until the year 1869 that the gipsy 

 moth {Porthctria ■-- Liparis disfar) was known to 

 have been colonised on the American continent. 

 Like some pests in other parts of the world, it 

 appears to hare been introduced through the 

 enthusiasm of an admirer. This act has been 

 attributed to I'rof I.. Trouvelot, a naturalist and 

 astronomer, who was at that time connected with 

 the Harvard University In his case it was not so 

 much any especial admiration for the species as 

 that he required it during certain experiments with 

 Blk-producins; moth., having the object of pro- 

 ducing a hardy hybrid which would withstand the 

 exigencies of climate and the attacks of fungoid or 

 other encr: 



billed 

 effort for the n 



moths was ncccuary in (he town where the 

 Professor had introduced them This was in 



Medford, near Boston, Massachusetts. There 

 seems to be no doubt that I'rof. Trouvelot realised 

 the danger of the caterpillars escaping, for when 

 the catastrophe happened he at once gave public 

 notice of the fact, and did all possible to 

 repair the mischief. It was, however, too late; 

 though no signs were seen of either moths or 

 their larvae for many years, the time came when 

 the latter were stripping off the foliage of most of 

 the ornamental and shade trees throughout the 

 region. In a report upon the whole question, 

 which has been recently prepared under the direc- 

 tion of I'rof I. llov.aol, 1 In- Entomologist 

 to tin: United States l>''|>artment of Agriculture, 

 the slow pr< 1 the establl ihmenl "f this 



in America is attributed to the time 

 required !■■' il to adapl il wll to ihe severe climate 



from fifteen to twenty years foi the gipsy- 

 moth to become abundant enough to command the 



