22 PKOCEEDIKGS or THE 



Pago 



G. The BECiNNMNd OF Mimicry : the FinsT Stei- 44 



a. The Beqhniivg of Nimicry iv the Norfh American Nynrjilialine 

 JJuficrJIi/, Linienitis arcliipjnis. 



II. Mimicry ketween the Difeeuent Insect Ouders 48 



I. COKCLUSION 49 



AiTENDix: The Pattern Edges in Paiks op Heliconine Forms 51 



A. Introduction. 



New and illuminating ideas not only displace much that is 

 erroneous, tliey unfortunately also tend to disturb much that 

 is true. One old-esTahlisbed truth, as it has been held to be and 

 as 1 hope to show it to be, forms the subject of the present 

 addi-ess. 



The evidence for the hereditary transmission of small varia- 

 tions which I propose to lay before you has been yielded by the 

 Lepidoptera, and nearly nil of it by butterflies. The special value 

 of the Lepidoptera in the study of variation was strongly insisted 

 upon by A. R. Wallace in his great memoir * read before the 

 Linnean Society on Mai'ch 17, 1864. The strength and amount 

 of the evidence might, I believe, be indefinitely increased but for 

 the fact that breeders have been led to select the larger rather 

 than the smaller differences as the more conclusive illustration of 

 Mendelian theory, or, from a very different but insistent motive, 

 as more successful in filling their cabinets with striking specimens. 

 But I hope to show that a considerable body of evidence exists, 

 and it is only necessary to direct attention to the fundamental 

 importance of the enquiry to ensure that searching tests ^\ ill be 

 applied in many directions. 



It is to be observed that I am not dealing on the present 

 occasion with heredity as Mendelian or n on -Mendelian. I am 

 concerned to prove that small variations are inherited, whatever 

 be the laws that govern their inheritance. I am indeed disposed 

 to think that this address would have been superfluous if serious 

 attempts had been made, with the right material, to answer the 

 question — ' what are the smallest variations subject to Mendelian 

 heredity ? ' One example to be described in later pages (see 

 pp. 25, 26) seems sufficient to prove that they may be very small. 

 In speaking of Mendelian heredity, I take this opportunity of 

 calling attention to the fact that, sliortly before his death, the 

 late G. J. llomanes independently discovered the reappearance of 



* Tranmciionn, toI. xxv., 186(i, p. 1. See especially p. 22 and the 

 following paseage on pp. 1-2: — "This delicately painted siirCace [of the wings] 

 nets as a I'ogister of the minutest did'erences of (irganization, — a shade of 

 colour, an additional streak or spot, a slight modification of outline con- 

 tinually recurring with the greatest regularity and fixity, while the body and 

 all its other members exhibit no appreciable change. The wings of Butterllies, 

 as Mr. Bates has well put it, 'serve as a tablet on which Nature writes the 

 Btory of the modifications of species.' " See also the jirefcnt writer's " Essays 

 on Evolution," Oxford, ]9U8, pp. .50-r>4, and tlie references there given. 



