122 PROBLEMS OF GENETICS 



718) were of this feminine type, but on the hills some 300 feet 

 above only 19 per cent, (in 3,230) were like the females. At 

 Castillejo, not far from Toledo I found no such male in 75 speci- 

 mens. 



Mr. Doncaster collected from several localities, especially 

 from two areas near Malaga, about 5 miles apart. In one of 

 these the female-like males were, as usual, in a minority, but 

 in the other these were actually in great excess, amounting to 

 about 81 per cent, in the 173 taken. Doncaster found a doubtful 

 indication that the composition of the population varies with 

 the season, which is quite possible, but it is most interesting 

 to note that in my chief locality after the lapse of ten years he 

 found the proportions very much the same as I had done at the 

 same season, for where I had 19 per cent, of the female-like males 

 his collecting gave 16 per cent. In other respects also, his sta- 

 tistics corresponded very closely with mine. 6 



The various forms of Heliconius erato are well known to en- 

 tomologists. They are strikingly distinguished by the colours 

 of the strong comb-like marking on the hind wing, which may be 

 red, yellow, green or blue. In various parts of the distribution 

 in South America sometimes two and sometimes three of these 

 distinct types co-exist. 7 



The distribution of the varieties of Noctua castanea typifies 

 a large range of cases. The form which is reckoned the normal 

 of the species has red fore-wings. It is practically restricted to 

 Great Britain and Germany, according to Tutt. The other 

 common form, neglecta, has grey fore- wings, and in this pattern 

 it ranges through West Central Europe from North Italy to 

 Germany. In the British Isles it extends up to Orkney. In 

 Britain this grey form is by far the commoner, occurring where- 



6 Doncaster, L., Proc. Zool. Soc, 1905, II, p. 528. 



7 I am not aware that the details of this striking case have ever been worked 

 out. It should be noted that the green and blue forms are not due to simple modi- 

 fication of the red pigment; for these colours, due to interference, fork over the 

 area occupied by the red lines. The distinctions between these forms cannot 

 therefore be simply chemical, as we may suppose them to be, for instance, in the 

 case of many red and yellow forms, and the genetic relationships of the Hehconid 

 varieties would raise many novel problems and be well worth studying experi- 

 mentally. 



