( Ixxvi ) 



requires reconsideration. It is certainly with great satis- 

 faction that I am enabled to state that Prof. Lloyd Morgan 

 has recently given us in his work bearing this title a contri- 

 bution of a very high order of importance. The author, as 

 the result of carefully conducted observations on young 

 birds and a very complete analysis of the evidence at present 

 available concerning young mammals, is disposed to accept 

 the view of the non-transmissionist school with respect to 

 acquired habits. It would be impossible to give here an 

 adequate notion of the contents of the book ; but in 

 view of the wonderfully fascinating problems of habit and 

 instinct offered by insects, I can with confidence invite tlie 

 attention of entomologists to this latest discussion of the 

 subject.* 



The bearing of these remarks on the question before us 

 — the utility of specific characters — is simple enough. A 

 difference of habit presupposes some difference of nervous 

 function, which again necessarily implies some difference of 

 structure. Until we know the complete life-habits of species 

 in nature, it would be rash to state that the systematist has 

 not included in his diagnosis some external characters corre- 

 sponding with these internal differences. The probability is 

 that he would, perhaps unconsciously, if he knew the organ- 

 ism only as a museum specimen, include such characters in 

 his description. But the external signs of internal differences 

 of vital iir.portance to the welfare of the species might be 

 quite trivial, and, when considered quantitatively, might be 

 pronounced valueless from the Darwinian point of view. Any 

 systematist who adopted this course would be liable to fall 

 into serious error. If the theory of natural selection has 

 taught us anything with regard to species describing, it has 

 brought into greater prominence than before the import- 

 ance of trivial differences — not as of direct selection value, 

 but as the outward and perhaps the only detectable sign of 



* Two very interesting papers iDearing on the development of the habits 

 of social Hymsnoptera have been published during the year by Dr. Paul 

 Marchal, viz. : " La Reproduction et lEvolution des Guepes " (Arch. Zoo. 

 Exp et Gen. [^] IV., 1-100) and " Observations sur les I'olistes " (Bull. Soc. 

 Zoo. Franc. XXL, 15-21). 



