thereon. " In considering the variation o( Arctia caia^wo. have 

 to deal with two classes of aberration. In one of these, 

 which, for convenience, I term the legitimate, we find every 

 gradation between the darkest and palest extremes. In the 

 other, which may be styled the abnormal, the aberration ap- 

 pears to be of an irregular character, and possibly the result 

 of influences about which we know very little at present. In 

 this class I place specimens which depart from typical lines 

 in the matter of colour, as for instance : examples with 

 coffee-coloured hind-wings, or buff-coloured markings on fore- 

 wings. The buff-colour can be produced by artificial means, 

 and I exhibit two specimens upon which I have operated. 

 Abnormal coloration occurs in otherwise perfect and well- 

 formed specimens, and in such cases it is difficult to offer a 

 suggestion as to the probable cause of the change in colour. 

 In other specimens there is abnormal coloration in con- 

 junction with more or less malformation of the \vings, but 

 there is no evidence to show that the change in colour is due 

 to the malformation. Although it is quite possible that the 

 cause of change in colour is also the cause of malformation, 

 it must be admitted that each may have resulted from quite 

 different causes. Suppose we argue that malformation is the 

 direct result of injury to either larva or pupa we should 

 probably be correct ; but it does not follow that injury to 

 the larva or pupa is also the cause of changed colour in the 

 wings, because we can have a colour change without mal- 

 formation, and malformation without change of colour. 



Returning to what I term legitimate varieties, I exhibit 

 figures of two very different forms oiA. caia ; one approaching 

 the darkest, and the other the lightest limits of the insect's 

 variation ; and also a number of specimens showing various 

 modifications, and to which I have already directed your 

 attention. If we collect larvae of A. caia from any district, 

 we shall find that the specimens bred therefrom exhibit 

 more or less difference in the amount of dark colour. We 

 rarely, however, get such aberrations as those figured. Now, 

 there are two questions which suggest themselves in this con- 

 nection : Are these rare varieties the immediate result of some 

 occult influence of which we have no knowledge? or are they 

 the offspring of well-matched parents? It occurs to me that 

 increase or decrease of dark colour is really due to what may 

 be termed ' accident of birth.' If, for instance, both parents 

 have more than the normal amount of dark colour, most of 

 the offspring will inherit this dark colour, and some will 

 probably be even darker than the parents. Of course, I only 



