of certain lepidopterous larva and pupce. 49 



ligustri in one hand and a twig of its food-plant in the 

 other, the wonder we feel is not at the resemblance, but 

 at the difference ; we are surprised at the difficulty 

 experienced in detecting so conspicuous an object. And 

 yet the protection is very real, for the larvge will be 

 passed over by those who are not accustomed to their 

 appearance, although the searcher may be told of the 

 presence of a large caterpillar. An experienced ento- 

 mologist also may fail to find the larv£e until after a 

 considerable search. This is general protective mimicry, 

 and it depends upon a general harmony between the 

 appearance of the organism and its whole environment, 

 so that the former does not attract attention. It is im- 

 possible to understand the force of this protection for 

 any larva, without seeing it on its food-plant and in an 

 entirely normal condition. The artistic effect of green 

 foliage is more complex than we often imagine ; number- 

 less modifications are wrought by varied lights and 

 shadows upon colours which are in themselves far from 

 uniform. We are unable to appreciate the significance 

 of larval colours apart from the food-plant, because we 

 do not comprehend all the factors that combine to form 

 the whole appearance of the latter. General protective 

 mimicry is such an appearance in an organism that the 

 artistic effect of its surroundings is sufficiently repro- 

 duced in it to prevent attention from being attracted 

 when the one is seen in the midst of the other. A 

 better instance of this general protection is seen in the 

 larva of Papilio Machaon. Here the protection is very 

 real when the larva is on the plant, and can hardly be 

 appreciated at all when the two are apart. The terms I 

 propose seem to express the difference between these 

 two forms of resemblance, protection being gained in 

 the one case by the production of a general effect, in the 

 other by the acquisition of a special appearance. I am 

 aware that general protective resemblances have been 

 already appreciated, especially by Weismann, in the 

 work to which I have alluded. I believe that this is the 

 first attempt to separate the two, and to confer dis- 

 tinctive names upon them. As might be expected, the 

 two classes are connected by intervening forms — by 

 organisms that are protected in both ways. Thus the 

 larva of S. ligustri has doubtless some special resemblance 

 to a series of leaves, each leaf being represented by the 

 green colour between two of the purple and white stripes. 



TRANS. ENT. SOC. LOND. 1884. — PART I. (APRIL.) E 



