Hudson. — On the Senses of Insects. 19 



the insect, and are connected with special nerve-fibres. They 

 are much more numerous on some points of the creature than 

 on others. They occur in very large numbers, for instance, on 

 the proboscis of the common house-fly. The skin of insects is 

 so much harder and more insensible to outside impressions 

 than the covering of most other animals that special tactile 

 organs are necessary, and it appears that these hairs perform 

 the needed function. 



The possession of the sense of taste in insects cannot be 

 questioned. No one who has ever watched a bee or a wasp 

 can entertain the slightest doubt on the subject. It is, again, 

 probably by taste that caterpillars recognise 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. Special experiments 

 have, moreover, been made by various entomologists, particu- 

 larly by Forel and Will. Forel mixed morphine and strych- 

 nine with some honey which he offered to his ants. Their 

 antennae gave them no warning. The smell of the honey 

 attracted them and they began to feed ; but the moment the 

 honey touched their lips they perceived the fraud. Will tried 

 wasps with alum, placing it where they had been accustomed 

 to be fed with sugar. They fell into the trap and ate some, 

 but soon found out their error, and began assiduously rubbing 

 their mouth-parts to take away the taste. 



Will found that glycerine, even if mixed with a large pro- 

 portion of honey, was avoided, and to quinine they had a 

 great objection. If the distasteful substance is inodorous and 

 mixed in honey the ant or bee commences to feed unsus- 

 piciously, and finds out the trick played on her more or less 

 quickly according to the proportion of the substance and the 

 bitterness or strength of its taste. The delicacy of taste is 

 doubtless greater in bees and ants than in omnivorous flies or 

 in carnivorous insects. At the same time the sense of taste in 

 ants is far from perfect, and they cannot always distinguish 

 injurious substances. Forel found that if he, mixed phos- 

 phorus in their honey they swallowed it unsuspectingly and 

 were made very unwell. It cannot, then, be doubted that in- 

 sects possess a sense of taste. The seat of it can hardly be 

 elsewhere than in the mouth or its immediate neighbourhood ; 

 and in all the orders of insects there are found on the tongue, 

 the maxillse, and in the mouth certain minute pits, which are 

 probably the organs of taste. In each pit is a minute hair, or 

 rod, which is probably perforated at the end. 



Passing to the sense of smell, we find that there are good 

 reasons for supposing that most insects are well endowed in 

 this respect. The seat of the sense is supposed to be situated 



