2 



THE ENTOMOLOGIST S RECORD. 



direction in which the modifications shall take place, so as to produce 

 the results necessary to adapt the individual to its environment. The 

 external force (natural selection) is, therefore, directive. 



Professor Weismann has recently discussed this matter, but in his 

 attempt to prove Nageli and Askenasy wrong, he appears occasionally 

 to refuse to internal forces, powers which he afterwards grants, whilst, 

 in order to fortify the part that external forces play, he ascribes 

 to them a creative power,'-' which appears to us to be hardly in 

 accordance with the facts. Yet, taking his paper as a whole, the 

 views he puts forward appear to resemble those above suggested. The 

 variations (from which all possible modifications arise), he asserts, 

 are inherent in the germ, whilst towards the end of the paper he says 

 that utility guides variation, which appears to be practically synony- 

 mous with the position Ave have enunciated. 



With these preliminary notes, necessary to explain certain criti- 

 cisms we may offer from time to time, it may be well to briefly run 

 over the latest pronouncement on the subject. 



Referring in general terms to the principle of selection, Weismann 

 calls attention to the fiery criticism through which the principle has 

 passed, and refers to Huxley's well-known statement that " Even if 

 the Darwinian hypothesis were swept away, evolution would still stand 

 where it is," and suggests that Huxley would thus appear to " have 

 regarded it as not impossible that the hypothesis should disappear 

 from among the great explanatory principles by which we seek to 

 approach nearer to the secrets of nature." Weismann, however, 

 boldly asserts his belief in the principle, and sees in the doubts that 

 have been raised concerning the principle of selection only a natural 

 reaction from its over-estimation. " The principle of selection was 

 not over-rated in the sense of ascribing to it too much explanatory 

 efficacy, or of extending too far its sphere of operation, but in the 

 sense that naturalists imagined that they perfectly understood its ways 

 of working, and possessed a distinct comprehension of its factors, 

 which was not so." On the contrary, he asserts that, the deeper 

 naturalists penetrated into the working of selection, they found that 

 although its action upon the whole was clear and comprehensible, yet, 

 in detail, so many formidable difficulties were encountered which they 

 were unsuccessful in tracing out so far as related to the actual details 

 of the individual process, and, therefore, in fixing the phenomenon as 

 it actually occurred. The difficulty, as Weismann points out, is that 

 we do not know how great a variation must be to have a selective 

 value, how frequently it must occur to acquire stability, nor can we 

 assert in scarcely a single actual instance in nature whether an observed 

 variation is useful or not, and he further indicates the difficulties 

 in getting the necessary facts relating to these points, suggesting that 

 it seems almost impossible to observe sufficient individuals of a species 

 in all their acts of life, and to observe these acts with a precision 

 enabling us to say which variation did or did not have a selective 

 value, /.('., was a decisive factor in determining the existence of the 

 species. 



* " The opposition of our own day contends that selection cannot create, but 

 only reject, and fails to see that precisely through this rejection its creative etlieaey 

 is assured " (Weismann). We prefer not to regard this as creation of new, but as 

 modification of existent, conditions. 



