542 THE WONDER OF LIFE 



to green herbage, and sixty-five of the brown variety 

 to withered herbage, and found that the birds had 

 not noticed any of them within the seventeen days of 

 the experiment. But it was quite another story when 

 he reversed the arrangement. When he put twenty- 

 five green ones among brown herbage, all were killed by 

 birds in eleven days, while of forty-five brown ones on 

 green grass, only ten survived at the end of seventeen days. 

 Here we have definite proof of a selective death-rate, 

 definite proof of the protective value of the colour-resem- 

 blance. And happily the case does not stand alone. 



In some cases the colour-resemblance between the animal 

 and its immediate environment has a very simple explan- 

 ation. The sea-lemon Archidoris tuberculata is yellow when 

 it is eating the yellow sponge Dendoryx incrustans and red 

 when it is eating the red Esperella cegagrofhila. It is 

 thus coloured hke the sponge it is browsing on ; the 

 sponge's colour has directly affected it. This is an individ- 

 ually acquired character — a modification, and not to be 

 confused with inborn colour- changes — ^which we caU 

 variations. Whether the sea-slug is protected or not by 

 its modification, we do not know, but the point is that, if it 

 should turn out to be protected, the origin of the protec- 

 tion is obvious. 



Dr. A. Ch. HoUande, of Nancy, reports a very interesting 

 case of an insect apparently protected by its meals. The 

 flower-buds of one of the mountain- mulleins {Verbascum 

 nigrum) are pierced in autumn by the larva of a Curcuhonid 

 beetle called Cionus olens, which feeds on the violet hairs of 

 the stamens. The violet vegetable pigment (anthocyan) 

 eaten by the grub passes down the food-canal, and, in 

 the usual way, into the blood, where, however, it has an 



