Vital Heat of Cold-blooded Animals. 157 



while, in similar circumstances, I found it not to surpass a 

 quarter of a Centesimal degree. Melolontha solstitialis possesses 

 nearly the same vital heat as M. vulgaris. 



Mr Newport studied the vital heat of Lucanm cervus by 

 placing the ball of a thermometer under its elytra ; he found 

 it to be about 1°.58 of F. (0.88 of a degree Cent.) when the 

 insect was in repose, and 2°.52 F. (1°.4 C.) when agitated. 

 In my experiments on the same insect, fixed in an immoveable 

 posture, there appeared a proper heat of 0.39 of a degree of 

 F. (0.22 of a degree Cent.), and this rose to 0.9 of a degree 

 F. (half a degree Cent.) in another example of the insect in a 

 state of the most violent agitation. 



In all these experiments, the insects I observed were placed 

 in air saturated with water ; when I placed them in the open 

 air, their internal heat became scarcely superior to that of the 

 surrounding atmosphere, and was even at times below it. 



The following are the degrees of vital heat I have ascertained 

 to exist in certain other Coleoptera, placed in saturated air. 



Carabus auratus, Fab. 0.32 F. (0.18 C.) of a degree. 



mobilis, do. 0.32 F. (0.18 C.) do. 



Blaps mortisaga, do. 0.21 F. (0.12 C.) do. 



Cetonia aurata, do. 0.45 F. (0.25 C.) - do. 



Chrysomela tenebricosa, do. 0.61 F. (0.34 C.) do. 

 Scavabacus vernalis, do. 0.38 F. (0.21 C.) do. 



According to Mr Newport, the vital heat of Gryllus mridim- 

 mus rises to 4° .68 F. (2°. 66 C.) ; in my experiments on the same 

 insect I did not find it above 0.61 F. of a degree (0.34 of a 

 degree Cent.) In the open air this insect is colder than the 

 surrounding medium. 



Gryllus 'csrrucivorous^ Linn., and G, campestrls, appear, by my 

 observations, to have a vital heat of about 0.9 F. (0.4 E.) of 

 a degree. That of Gryllus grillotalpa, Linn., is less, not ex- 

 ceeding 0.28 F., or 0.16 of a degree Cent. 



The following are the degrees of vital heat which I have 

 found in certain Lepidoptera, respectively in the larva, nymph, 

 and perfect insect. 



Sphynx Stellarum, Linn, larva, . 0.198 F. (0.11 C.) of a degree. 



Id. perfect insect, . . 0.52 F. (0.29 C.) do. ^ 



Sphynx Tiliae, larva about to undergo 



its metamorphosis, . . 0.77 F. (0.43 C.) do. 



Id. nymph a month old, . 0^1 F. (0.34 C.) do. 



