212 Analyses of Books. tMARCH,' 



being incapable of going in search of the air, the air goes in 

 search of it," will still remain inviolate. 



" If it should be argued that the trachese are not found 

 charged ^vith blood after the death of the animal, it may be 

 answered, that neither are the arteries in the higher orders of 

 animals found charged with blood after their death. However, 

 I have actually seen some of the ramifications of those tracheae 

 which are connected with the cseca distended with a fluid of the 

 same colour as that found in those organs; and though 1 have 

 only witnessed this fact in two instances ; yet such a fact, even 

 singly taken, must be allowed to be of considerable importance. 



" Of one thing I am certain, that after careful observation, I 

 have never found the abdominal viscera, I will not say bathed, 

 as some authors of credit have expressed themselves, in the 

 nutrient fluid which is supposed to have transuded through the 

 coats of the intestines ; but I have not even found them lubri- 

 cated by a greater proportion of moisture than lubricates the 

 intestines of the higher classes of animals. 



" There is another difficulty which occurs to the hypothesis 

 of the transudation of the chyle through the coats of the intes- 

 tines ; for, if the blood be conveyed to the several parts by 

 previous general diff'usion through the interior of the body, and 

 then by absorption into the substance of particular organs, as 

 the hepatic tubes, the vesiculse seminales and the ovaries ; how 

 does it happen that the bile, for instance, does not transude 

 through the coats of the same vessels, the pores of which have 

 admitted the blood from which it has been formed? It may be 

 answered, that the alteration which the blood undergoes in the 

 several organs changes its properties to such an extent, as to 

 render it incapable of repassing through the pores which admit- 

 ted it. I cannot of course presume to say that such is not the 

 case ; and I am aware that many entomologists will be surprised 

 at, and perhaps disinclined to listen to, the opinion here advanced 

 with respect to a sanguineous circulation in insects ; but I 

 nevertheless hope that the opinion will not be rejected without 

 some previous attention to it. With regard to the dorsal vessel 

 of the gryllotalpa, which in this, as in other insects, has been 

 supposed to stand in the place of an arterial heart, I have very 

 few observations to offer. It does not aoree in its form with the 

 description commonly given of this mysterious organ ; for 

 though it diminishes in diameter as it approaches the head, this 

 is by no means the case towards the other extremity of it. I 

 have not yet completely succeeded in tracing this vessel to its 

 anterior extremity ; because as it approaches its termination in 

 that direction, it becomes so delicate as to have hitherto broken 

 under dissection before I arrived at the extremity of it. Towards 

 the opposite extremity, it gradually becomes larger from the 



