CRUSTACEA— INSECTS. 23 



suspects to be ganglionic cells, and he suggests that the 

 organ is one of taste. 



Even in the Crustacea (crabs, lobsters, etc.), though 

 we can scarcely doubt that they possess the sense of 

 taste, no organs have been yet described to which it 

 can be with any confidence ascribed. Huxley, for 

 instance, in his work on the Crayfish,* says, "It is 

 probable that the crayfish possesses something ana- 

 logous to taste, and a very likely seat for the organ of 

 this function is in the upper lip and the metastoma, but 

 if the organ exists it possesses no structural peculiarities 

 by which it can be identified." 



As regards insects, the possession of the sense of taste 

 cannot be questioned, though, except perhaps in many 

 Hymenoptera and certain phytophagous insects, it may 

 not be of great importance. No one who has ever 

 watched a bee or a wasp can entertain the sliglitest 

 doubt on the subject. It is, again, probably by taste 

 that caterpillars recognize their food-plant. Moreover, 

 this is partly the effect of individual experience, for, 

 when first hatched, caterpillars will often eat leaves 

 which they would not touch when they are older, and 

 have become accustomed to a particular kind of food.t 

 Special experiments, moreover, have been made by 

 various entomologists, particularly by Forel and Will. 

 Forel mixed morphine and strychnine with some honey, 



* " The Crayfish : an Introduction to the Study of Zoology." 

 + A remarkable case is afforded by those species in which the food of 

 the larva and perfect insect is different, so that the mother has to select 

 and find for her offspring food which she would not care to touch her- 

 self. Thus while butterflies and moths themselves feed on honey, each 

 species selects some particular food-plant for the larvae. Again, flies, 

 which also enjoy honey themselves, lay their eggs on putrid meat and 

 other decaying animal substances. 



