19 



ence is analogous to electric energy, or is at least 

 obedient to the latter, and made to flow at its com- 

 mand ; Mr. Thackrah shows that the vitality of the 

 blood is maintained by nervous influence ; and Dr. 

 Cams of Dresden discovered the circulation of blood 

 in insects, and that the decrease and increase, with its 

 intermission in the light, of the Lampyris italica, cor- 

 responded with the pulsation of the blood. Just so is 

 it with the chameleon : the temperature of the blood 

 is proved variable, and the colour cast up on the skin 

 is its index. It may not be irrelevant to the question 

 to state, that the blood is presumed to be warm in pro- 

 portion as it is nearest the heart, and that arterial 

 blood exceeds, by about one degree, that of the 

 veins. By Mr. Hunter's experiments^ it appears a 

 moderate degree of inflammatory action is capable of 

 elevating the temperature of the blood 4? F. ; and it is 

 evident that irritation or excitement produces an 

 action somewhat analogous. Violent passions of the 

 mind cast up their crimson or roseate hue on the skin, 

 and we feel the fevered warmth playing on the face. 

 The range of temperature we observed on the skin of 

 the chameleon rose from 70 .5 to 74, nearly the 

 difference observed by Mr. Hunter between the ordi- 

 nary state of the blood and that of common inflam- 

 matory action. Specific colours have invariably pecu- 

 liar and specific temperatures, and the advance from 

 the violet to the red ray of the prism is accompanied 

 with a corresponding elevation of temperature. The 

 variable changes in the chameleon are often instanta- 

 neous, though sometimes more slowly produced. 



In pursuing these remarks and investigations, we 

 were surprised and gratified to find that somewhat 

 similar views and conclusions had been sustained by 

 Panarolus, a Roman writer, quoted by Ogilby in his 



