EXTOMOLOGY, F.VOLUTIOX, AND ROMANCE. 31 



" You cannot leave out geology." No ! and we do not want to, but 

 we do want to trace out a parallel between the life-history of each 

 species and its probable evolutional history, as told to us in very 

 fragmentary evidence by fossils. 



In reference to the tirade against the written works of Darwin, 

 Huxley and Tyndall, I can only echo the sentiment of the editorial 

 foot-notes. 



As for the " neAV departure," the idea is pretty, and if it could be 

 put into practice I believe that all good naturalists, whether of our 

 particular cult or otherwise, would welcome it ; but I don't think that 

 " the man in the street " would come in great numbers, even to see 

 living insects and to learn what a " living museum " could teach about 

 them. Is there not at Westminster a large building erected for the 

 purpose of letting " the man in the street" have an opportunity of 

 studying the habits of living fish ? Has it been a great success ? 



By all means let us do all we can to educate the crowd to a due 

 appreciation of the charms of nature, but at the same time do not let 

 us quarrel with those who are ahead of the crowd, and are prying 

 further and further into nature's secrets, even though the facts that 

 they elucidate may seem, when taken separately, to be uninteresting to 

 the o-eneral. 



MIMICRY. 



II. The origin of protective wing markings. Internal forces plus 



SELECTION AND UTILITY. 



By J. W. TuTT, F.E.S. 



In our previous considerations {autf, pp. 1 — 4) we have reached the 

 point at which " selection and utility," on the one hand, and purely 

 "internal forces" on the other, have been suggested as the cause of 

 the complicated protective wing-markings found in many butterflies. 

 In this we shall attempt to show that both " internal forces," and 

 " selection and utility " take part in their production. 



The complexity of many wing-markings is stated, by Weismann, 

 to be due to the inheritance of the patterns of all the ancestral 

 species, the inherited patterns having been eli'aced, preserved, or 

 modified as new designs became necessary. But, although the 

 markings rose conformably to law, yet " the laws involved, i.e., the 

 physiological conditions of the variation," have been subservient to 

 the ends of a higher power — utility, which primarily determines the 

 kinds of colours, spots, streaks, and bands that shall originate, as 

 well as their method of disposal. The physiological conditions 

 " come into consideration only to the extent of conditioning the 

 quality of the constructive materials — the variations, out of which 

 selection fashions the designs in question." With this we quite agree. 

 Internal forces condition the quality of the material ; selection, guided 

 by utility, fashions the designs. 



It is the principle that the formation or fashioning of these 

 patterns is brought about by internal forces, to which Weismann 

 objects. He states that formative laws of the kind suggested by his 

 opponents, imply that "definite spots on the surfaces of the wings 

 are linked together in such a manner by inner invisible bonds, as to 



