304 Mr. E. B. Poultou. Essential Nature of the [Apr. 23, 



Food-plant. 



Effect on S. Ocellatus. 



Colour of undersides 

 of leaves. 



Crab (cultivated) 



Probably variable. I have found yel- 

 lowish, varieties on " yellow Siberian 

 crab." My experiments showed that 

 larva? with a tendency towards 

 whitish were not modified. 



Undersides vary from 

 green to white, but 

 are smoother than 

 apple, and some- 

 times glabrous. 



Crab (wild) .... 

 Var. Acerba 



Probably strongly towards yellowish, 

 but only one observation (which 

 supported this view) . 



Undersides distinctly 

 green and glabrous. 



S. Yiminalis . . . 



Apparently contradictory results. From 

 a fair number of observations in the 

 field (with only one exception) I 

 have assumed that the effect is 

 towards the whitish variety. Mr. 

 Meldola's instances, which are about 

 18 in number) oppose this conclu- 

 sion. My breeding experiments per- 

 haps supported Mr. Meldola's in- 

 stances rather than my own, but 

 they were not very conclusive. My 

 experiments showed that this plant 

 does not produce so white a green 

 as apple, and this I think is the 

 case. But it certainly does not 

 cause so yellow a green as S. rubra. 

 I am still inclined to think that it 

 may tend towards whitish, but the 

 experiments must be repeated. 



Undersides white, with 

 dense satiny down. 



S. SmitMana . . . 



Two instances, one inclining towards 

 the yellow side of intermediate, one 

 towards the whitish side. The lat- 

 ter, I think, represents the real ten- 

 dency. 



Undersides white, with 

 dense satiny down. 



S. Ferruginea,* 

 Anderson 

 (probably) 



Four instances upon a single tree, doubt- 

 fully referred to this species by 

 Eev. J. E. Leefe. The leaves were 

 exactly like those of S. SmitMana, 

 only smaller. Three of the larvae 

 inclined towards the whitish side of 

 intermediate, while one was bright 

 yellowish - green. The former is 

 doubtless the real tendency, and if 

 so, indirectly supports my impres- 

 sion as to the tendency of S. Yimi- 

 nalis. 



Undersides white and 

 rather silky. 





Only one instance, the yellowish va- 

 riety, upon a tree of which the 

 leaves had dark or glaucous under- 

 sides, and were not downy (at any 

 rate distinctly). This probably re- 

 presents the tendency of that par- 

 ticular tree, but in many cases it is 



Undersides reddish, 

 glaucous, or asby, 

 downy sometimes 

 and varying in the 

 amount of down 

 when present. A 

 very variable species. 



* See note upon this species in paragraph 16. 



