MTJITCRY. 33 



There seems to be no reason why, if internal laws were assumed to 

 control the markings on butterflies' wings, they should not be 

 as complicated as if controlled by external forces. On the contrary, 

 we are ready to admit that any number of combinations might occur 

 in the markings even as a result of internal forces, for Weismann 

 has elsewhere explained to us that the determinants which give rise 

 to the various structures are largely independent, and that, therefore, 

 the determinants which produce respectively the scales of the 

 upper and under surfaces, may be, and probably often are, de- 

 veloped quite independently, and therefore may be modified quite 

 independently. We have no doubt ourselves that " the root of the 

 internal selective processes lies in that place where it is determined 

 what variations of the parts of the organism shall appear," and that 

 when the internal forces have produced the variations, and condi- 

 tioned the quality of the constructive materials, then selection directed 

 by utility fashions the designs. It seems to us that, in producing 

 the final result, either the external or internal force is impotent 

 without the other. 



But, when it comes to the consideration of the actual designs and 

 patterns that the combinations have taken, then we confess that the 

 supposition that they have been developed by internal forces, appears 

 untenable, and we are quite ready to agree that the particular combi- 

 nations have been brought about as suggested by Weismann. Utility, 

 there can be no doubt, does show us in what direction it has caused 

 natural selection to act, and does show us why the various mimetic 

 patterns have been evolved, and we can suggest no other factors but 

 selection, guided by utility, capable of evolving them. 



On the value of rare British Lepidoptera. 



By Rev. .J. GREENE, M.A., F.E.S. 



In the April number of the Kiitoinolot/ist's Record is an article signed 

 " John Bull," in which I think I recognise the hand. Be this so or 

 not, I wish to express my most cordial approval of every part of it. 



I have long since ceased to care for " Rarities," so-called, and have 

 removed from my small collection such species as Paclictra leiwophaca, 

 Ennnmos autumnana, and others. I have noticed that after a sale, 

 you, and others, have remarked that such and such a collection (or 

 certain rare insects in them) went for comparatively nothing — 

 assigning as the reason the absence of any " history " of it. or its con- 

 tents, such as " labels," " locality," " from whom received, etc." But 

 of what value is such a history ? What is to prevent a collector or 

 dealer from attaching such a label, or locality or name, to any insect 

 that he thinks wortii the trouble "? In these days of importation — of 

 eggs, pupBB, etc. — of what value is the declaration — honest or dishonest 

 — that the insect was bred by self, on such a day, and in such a 

 locality ? I would not accept as a gift any rarity or novelty captured 

 during the last thirty years. The donor, whether amateur or dealer, 

 may be absolutely honest, but — " Quis custodiet custodes?" How is 

 he to prove that he himself is not the victim of a fraud ? As to 

 "dealers," I have bought for many years insects from Messrs. 

 Harwood, W. and T. Salvage, but they know that I never buy a 

 " rarity." My experience goes back to a period when the " dealers " 



