144 



CORRESPONDENCE. 



"A Plague o' both your Houses!" 



Under this appropriate [?] heading Natural Science (vol. x., p. 4) makes the 

 statement: — "Our need still is for facts . . . we would suggest that the present is 

 not the time for speculation on the merits or failings of Natural Selection. ... A 

 truce to library papers for ten or twenty years ! . . . Perhaps, at the end of the 

 suggested period, it may be possible to formulate important results based on 

 experimental evidence, say, for instance, whether variation is indefinite or definite." 



As you say that you were "urged to the above remarks" by my paper : — " Does 

 Natural Selection play any part in the Origin of Species among Plants," perhaps 

 I may venture to say that I have done, and that, too, for tiventy years, precisely 

 what you now advise me to begin to do ! As you say " no new experiments were 

 advanced " by me, I can only presume that you have not done me the honour to 

 read my book on " The Origin of Plant Structures," in which plenty of experiments 

 are recorded. 



I would also like to observe that it is no question of " speculation " or of pitting 



one theory against another, for the conviction that dejinite adaptation is all-sufficient to 



account for the origin of species, is forced upon me by the accumulation of positive 



facts, which speak for themselves. No theorising is required at all. The origin of 



species by means of natural selection is still, as I pointed out, an unverified deduction ; 



whereas adaptation by definite variations is proved, not only by a vast accumulation 



of parallel series of facts, i.e., by induction, but has been verified abundantly by 



experiments. If this be not sufficient to convince Darwinians, I venture to think that 



nothing ever will. Conversely, until they can prove the universal existence of 



indefinite variations. The Origin of Species by Means of Natural Selection must 



remain a baseless hypothesis. 



George Henslow. 



[ We have not only read but reviewed Mr. Henslow's book (vol. viii., p. 201), 

 nay, more, we recommended it. We implied in the Note of which Mr. Henslow 

 complains, that in his paper at the Linnean he advanced no new experiments. If he 

 did adduce any fresh experiments conducted by himself since February, 1895, we 

 will admit our error, and shall be pleased to publish the details of them. — Ed.^ 

 Nat. Sci.] 



Natural Science for March, 1896, alluded to Dr. J. D. F. Gilchrist's method 

 of killing Aplysia in an expanded condition, by cocaine. In May, 1896, Mr. H. 

 Hanna wrote to us that a i per cent, solution of chromic acid was " simply perfect " 

 for the purpose. Dr. Gilchrist now writes to us from Cape Town as follows :— " I 

 have, at Naples and elsewhere, repeatedly used a i or 2 per cent, solution of chromic 

 acid— the method at present in use at Naples— and, after many trials with this and 

 other methods, have come to the conclusion that the method I recommend is the 

 most satisfactory." 



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