BARON CUVIER. 35 



s not a true heart, and that it does not furnish any means 

 )f circulation, 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, encircling all parts, is secreted by simple imbibition. 

 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 compos- 

 ed of spongy tubes, sometimes folded back upon themselves, 

 intimately united by tracheae, and which may be always 

 unrolled when time and patience are called in to aid the 

 task. All these observations were attended with a result 

 which is always gratifying in natural history ; they estab- 

 j lished insects in a very natural and distinct class, and, like 

 (other well-directed labours, and well-founded remarks, 

 I these discoveries induced others to make the same research- 

 es, and a new field was opened to the Entomologist. If 

 M. Cuvier was at any time doubtful, he did not hesitate 

 saying so : he corrected himself when he had been mistak- 

 en ; and even at this period, when he had all his fame to 

 make, so far from being annoyed at (he endeavours of 

 others, he was the first to encourage them, to give them 

 his honourable suffrage, and to receive as friends those who 

 ventured into his province, in order to settle a doubtful point 

 of science. 



The mode of circulation in the Annelides was not better 

 determined than that of insects, and M. Cuvier also turned 

 his attention towards them. It was in pursuing .this in- 

 quiry that he told anatomists, that the red colour of the 

 liquid contained in leeches does not in the least proceed from 

 the blood which the animal has imbibed, but that it is their 

 own blood which circulates in four principal vessels. This 

 important observation separated leeches, and animals ana- 

 logous to them, from those with white blood ; and caused 

 Lamarck to give the class to which they belong the distinct 

 name of Annelides. In M. Cuvier's great work on Com- 

 parative Anatomy, all the peculiarities belonging to insects, 

 and other articulated animals, were afterwards given ; and 

 as he carried his labours into a wider expanse, he left their 



