BARON CUVIER. 59 



in which insects are nourished. Having esta- 

 bhshed that the dorsal vessel is not a true heart, 

 and that it does not furnish any means of circu- 

 lation, it was necessary to account for the way 

 in which the nourishing fluid is carried to all the 

 organs. M. Cuvier proved that this juice passes 

 through the cells of the intestinal canal, that it 

 spreads over the interior of the body, and, en- 

 circling all parts, is secreted by simple imbibi- 

 tion. In this memoir he also stated, that the 

 secreting organs of insects are not solid glands, 

 as in all those animals which possess a heart and 

 blood vessels, but that they are composed of 

 spongy tubes, sometimes folded back upon them- 

 selves, intimately united by trachese, and which 

 may be always unrolled when time and patience 

 aie called in to aid the task. All these observ- 

 ations were attended with a result which is 

 always gratifying in natural history ; they 

 established insects in a very natural and distinct 

 class, and, like other well directed labours, and 

 well founded remarks, these discoveries induced 

 othe'rs to make the same researches, and a new 

 field was open to the Entomologist. If M. Cu- 

 vier was at any time doubtful, he did not hesitate 

 saying so : he corrected himself when he had 

 been mistaken ; and even at this period, when 



