BOOK OF NATURE LAID OPEN. 85 



In the head of an insect no organization of the 

 brain is said to be discovered, but the want of this is 

 abundantly made up by that medullary thread which 

 communicates the vital principle to the other parts of 

 thejr bodies, and endows them with that tenacity of 

 life, which, as has been already observed, is so use- 

 ful to the species. Neither are they apparently fur- 

 nished with the usual organs of smelling and hearing, 

 but whether the olfactory nerves communicate with 

 the feelers, and the auricular organs are situated in 

 the antenna?, as Mr. Barbutt supposes, or not, there 

 can be no doubt from the readiness of Wasps, 

 Flies, &c. to betake themselves to their wings and 

 fly to dainties at a distance; and the alertness oi Bees 

 in sallying out to the relief of a brother in distress, 

 when he alarms them by his noise outside the hive, 

 that insects are not deficient in the senses of hearing, 

 wherever the organs may be situated. The manner 

 of respiration is different in insects from other ani- 

 mals ; they breathe through pores placed in the sides 

 of their bodies, and this also fits them for that re- 

 markable peculiarity of living in separate parts. In 

 the composition of insects no bones are made use of, 

 but this defect is supplied in some by a membraneous 

 or muscular skin, and in others by a crustaceous or 

 horny covering Their eyes are fixed, and they have 

 no eyebrows, but, to prevent them from injury the 

 latter want is supplied by the external tunic of their 

 eyes being hard and transparent, and to remedy the 

 former, some insects have four, some six, others. %ht, 

 while the number of lenses in some of those who 



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