148 



Pale and wet. 



THE entomologist's RECORD. 



Suitable to wet. 



Pale and dry. 



Dark and wet. 



Dark and dry. 



Suitable to dry. 



" Diagram^ illustrating hypothetical race varying indepen- 

 dently in colour and adaptability to climate. Individuals may 

 be arranged in a square as above. When subjected to varia- 

 tions of climate, the race will take the form (compared with 

 the original hypothetical race) shown by the curved line." 



Nothing, I think, can be clearer than these ideas of Dr. 

 Chapman, and there is no doubt they will direct attention to 

 the subject in a different way to which it has ever been 

 directed before. We all know of the existence of melanism ; 

 we have all seen that it is intimately connected with humid 

 areas, and that similar conditions produce almost identical 

 results in our own country, on the Continent, and in New 

 Zealand. But no attempt has, I think, before been made to 

 point out the exact way in which the active factors producing 

 melanism, work. For myself, as may be gathered from what 

 I have before written, I have no faith in the results of the 

 so-called temperature experiments of Mr. Merrifield, nor do I 

 yet accept the suggestion that cold produces melanism, but 

 the slightest modification of Dr. Chapman's theory to exclude 

 cold and substitute moisture as the active agent in the produc- 

 tion of melanism would satisfy my ideas exactly. It must be 

 owned that we are simply on the threshold of this all-absorb- 

 ing and interesting subject, and in a very short time new 



^ In this diagram 7 dots are used each way. Had 5 been used each way, the 

 numbers in the previous paragraphs could have been applied direct to this diagram. 

 As it is, the same method of reasoning is applied, but A (the typical individual) 

 becomes here 4-4 an 1 not 3-3 as in the previous diagrams, and so on with the other 

 numbers. — ^J.W.T. 



