( -isi) ) 



comparative!}' very few antliors * have given expressiou to tlie opiuiou, not only 

 tlaat tliere is a certain amount of variability fonnd in those organs, bnt that one 

 can by no means rely upon them iu the judgment of specilic distinctness or uou- 

 distinctuess. During our researches on the Eastern Papilios f we came across some 

 striking cases of variability of the copulatory organs wliicli made it evident to us 

 that the above assertion of an extensive variability was not the ontcome of sujjer- 

 ticial research, and this induced tlie Honourable Walter Rothschild to charge me 

 with investigations in the matter. As Mr. Rothschild knew from the study of 

 the external characters of the Eastern Papilios that a decision about the specific 

 distinctness of these variable insects with some certain degree of correctness could 

 not be arrived at unless one had ascertained with some probability of correctness 

 the limits of individual variation of each form (no matter whether the form was 

 described as species or variety), and hence in order to come as nearly as possible 

 to the knowledge of the limits of variation it was necessary to compare a great 

 many specimens, he liberally pnt the long series of individuals of his collection at 

 my disposal, and to this the results of our investigations are largely due. It seemed 

 to us that in the first place the aim of our researclies had to be to ascertain whether 

 the alleged constancy of the genital armature was, at least iu most species, real, 

 especially as compared with the distinguishing characters derived from the wing- 

 pattern. A little consideration, however, showed ns that this was scarcely 

 necessary. First, if we accept the statement that every specifically distinct form 

 is to some degree different from the allied forms in the genital armature as 

 being true, it by no means follows that the inverse is correct, namely that forms 

 presenting in the sexnal organs some diflVrences from the allied forms are specifically 

 distinct. Hence the proof of the variability of the organs in question would not 

 imply that these organs .are useless for diagnostic purposes, though their taxonomic 

 value would certainly be lessened. Secondly, if two or more allied species arc 

 diiferent in the sexual oi'gaus we have to conclude from the theory of evolution 

 that the present differences are the outcome of divergent development of the 

 allied species from a common ancestral species which itself had the sexual organs 

 either different from all its descendant sjiecies, or from all but one ; if we concede 

 this, and all followers of Darwin have to do so, it is self-evident that the ancestral 

 species must have been variable in the sexual armature. As, therefore, in the 

 ancestors of our present sijecies the genital armatm'e must be assumed to have been 

 so variable that the variation could lead to specific separation, we cannot l)nt assume 

 ((.priori that in all the species of the present which are iu the state of diverging into 

 varieties the genital organs must exhibit not only some varialiility, but also variation 

 to such an extent that the genital characters of a certain variety could be increased 

 by the factors of evolution and ultimately be transformed into specific characters, 

 unless one tries to avoid these consequences eitlier by abandoning evolution alto- 

 gether, which would be acceptable, or hy maintaining tliat «'volution is not going 

 on during the present epoch, which would be ridiculous. 



This consideration made it jiretty clear to us that the more important part 

 of our investigations would have to be, not to prove the occurrence of variation 

 of the organs in question, but to ascertain the kind of variation, esjiecially to 

 accumulate such facts from wliicli couhl be seen wlielhor there is individual, 



* reres-, Ann. Sue. Kid. h'l: p. r-1 i^ls'.H) ; Eil\v:ircis, Camid. JCnt. p. ."iG (1S94) ; Kolbe, JEnt. Naehr 

 p. 133 (IS!- 7). 



t is'ov. zo )!,. p. 2i;;i (^is95). 



