( 430 ) 



The independent variability of organs found to exist among the individuals 

 derived from one/p//i((7e, or among the individuals flying in the same locality— in 

 short, among specimens about the specific identity of wliich there is no doubt — leads 

 us to the conclusion that the same organs of the same species vary also independently 

 in other localities. The distinguishing characters of a geographical race thus can be 

 shown to be independent of one another, and that the association of distinguishing 

 characters is not correlation of these characters, which is of the greatest inii)ortance, 

 if we come to consider the caiises of the divergence exhibited by such races, the 

 degree of relationship of the races, and the probable history of their geographical 

 distribution. We mention in this place only that, as the wing-form and wing-pattern 

 of the Papiiios vary independently of the copulatory organs, we shall find in the body 

 of this paper ample illustrations of those three phylogenetical and biological jiheno- 

 mena. The first we have to do is in every case to study the individual variation in 

 order to know which characters are correlated and which not in respect to variation, 

 then to study the characters of the same organs of the geographical representatives 

 of the same species, and finally to compare the results we arrive at, if we draw from 

 each single independent character conclusions as to subspecific and specific distinctness, 

 the influence of the evolutionistic factors, and the history of this influence. 



The occasional apjiearance of individuals, mostly single or in \-ery small numbers, 

 amongst the normal specimens, differing widely from the latter in one or more 

 points, we have to classify as a peculiar kind of di- and polymorphism. The so-called 

 sports and monstrosities, between which terms there is no line of delimitation, as 

 there is also no such line between normal and abnormal varieties, belong to this kind 

 of discontinuous variation, and it is a rather general assumption that the characters of 

 such sports and monstro.sities get swamped away by intercrossing. Is this really true 

 in the verbal sense ? If swamped away means " not appearing in the direct ofifsjiring " 

 of that abnormal specimen, it might often be correct ; but if it means disappearing 

 for ever, never reappearing among.st the individuals constituting the species, it is not 

 true. Many sports and even monstrosities are found again and again, as every collector 

 knows ; and when an exceptionally abnormal variety has been found once, there is no 

 reason for the assumption that it will not be fmmd a second time. In fact, the 

 collectors, who work with individuals, expect and hope to come across sucli a variety 

 themselves. If, for example, somebody had published this year that from one of his 

 pupae of Acherontia atropos (death-head moth) a specimen with entirely ochreous 

 wings had emerged, we are quite sure that all those who are in possession of a con- 

 siderable number of pupae of this insect would look forward to the emergence of the 

 imagines with the eager expectation to find such an individual among tlieni." 



The repeated occurrence of the same abnormal variety is, to our mind, of the 

 greatest importance, as the repetition of the phenomenon is a proof that the variety, 

 how abnormal and rare it ever may be, is not entirely swamped away from the species, 

 and that the constitution of the individuals of the respective species, taken as a whole, 

 is such that under certain circumstances, whichever they may be, the variety will be 

 produced, or even must be produced. It is, therefore, quite intelligible that, when 

 those certain circumstances become more frequent, the variety which we now call 

 abnormal might become normal. From this point of view, the record of unusual 

 varieties, including monstro-sities, is by no means so unimportant as it ai)pears to 

 be to the systematist who recognises only "distinct" species. On the contrary, we 



 For illuiitrations see Tiateson, Mnteriah hr i fitudy of Variatwii. London. 1891. 



