^^^^ AND ^^ 



JOURNAL OF VARIATION. 



No. 6. YoL. IV. June 15^3, 1893. 



]VIEL£]^Oepil^OI^]VI ipl Bl^II'lglJ IiEPIQOP'TEI^^. 



Bv A. R. GEOTE, M.A. 



Mr. Tutt's interesting impev, in reply to Mr. Robson, will have 

 drawn fresh attention to this important jjhase of Variation in the 

 Lepidoptera. The fact must be assumed as fully proven by Mr. Tutt 

 that " areas which are excessively humid, and those that had by 

 artificial change of environment, produced dark surfaces," have pro- 

 duced also melanic races of Lepidoptera. The darkenino- of the 

 resting places by rain and smoke, the (sui^posed) action of the'^moisture 

 on the larva, and finally, "natural selection," availing itself of the 

 physical environment and the inherent tendency of the si^ecies to 

 melanism, are accordingly claimed to have succeeded in producino- a 

 greater number of dark individuals. I think we may eliminate from 

 the problem the action of " natural selection " and the effect of 

 humidity on the larvte, because these are factors, the modus operandi of 

 which has not been, in the latter case scientifically, in the former 

 here only inferentially, explained or proved. There remains the fact[ 

 that in localities affording dark resting places for the moths, melanisni 

 is frequent. May not the explanation be that the dark restin"- iilaces 

 are protective '.' Granted the existing tendency to melanisuT, would 

 not a greater number of specimens of the dark forms be i^reserved 

 from natural enemies by their resemblance to their restino- i^laces in 

 colour ? Thus the collector, not being so easilj^ deceived would 

 obtain a greater percentage of dark forms from such localities. I take 

 it for granted that melanism is the result of reversion, and that it is 

 inherited. Melanic parents do not produce necessarily melanic 

 progeny, or at least, exclusively melanic races. Melanism occurs 

 sporadically with certain species, and this also in localities not particu- 

 larly wet, and not at all smoky. Certainly neither the " actinic " 

 theory, nor perhaps even the " natural selection " theory seems rightly 

 used to account for a phenomenon which has its basis in inheritance 

 and which displays itself more obviously in surroundino-s which aid in 

 its protection. Reversion is inheritance acting throuo-h laro-er intervals 

 It does not seem to be proven that a gi-eater total amount of dark 

 forms are absolutely produced in wet and smoky places. But, in such 

 places, the pale forms would be the first to be destroyed from their 

 contrast to their environment, and the consequent attention of their 



