PHYSIOLOGY. 271 



writer in the Dictionnaire des Sciences Naturelles, 

 " tends at least to prove, that the humming of bees 

 is not occasioned by a strong vibration of the in- 

 ternal part of the upper wings, but rather by a 

 tremulous affection of the entire body ; and per- 

 haps even by the escape of a greater quantity of 

 air through the stigmata or spiracles. This last 

 would amount to a sort of voice." The humming 

 noise with which a flower is always approached by 

 the bee, ceases as soon as she has alighted upon 

 it, though during the time that she is extracting 

 its sweets she is in a constant vibratory motion, 



CIRCULATION. 



The term circulation is not strictly applicable 

 to the imperfect sanguineous system of insects, as 

 the fluid which supplies their bodies with nutri- 

 ment is not distributed to its several parts through 

 the medium of a heart and vascular system. 

 Lyonnet and Cuvier are both of opinion that in- 

 sects have no heart, whereas all creatures that 

 possess a circulation, properly so called, have a 

 heart, lungs or gills, and a liver ; but insects have 

 only air-vessels and hepatic ducts. The chyle 

 which is produced in their intestines, transpiring 

 through the pores of the intestinal canal, passes 

 into the general cavity of the body, where it is 

 probably animalized, and made to answer the 

 same purposes that blood does to creatures of a 



