ORGANS OF CIRCULATION. 69 



the heart. To this alone is reduced the whole circu- 

 lation in insects, which accordingly have but one 

 artery without branches, and no veins. 



" The wings of the heart are not muscular, as 

 Herold pretends ; they are simple fibrous ligaments 

 for retaining the heart in its place. 



" The heart is divided within into eight successive 

 chambers, in the cockchafer, separated from each 

 other by converging valves, which allow the blood to 

 pass forwards from one to another as far as the artery 

 that conducts it into the head, but oppose its move- 

 ment backwards. Each chamber is furnished at its 

 fore part on the sides with two openings in form of cross 

 chinks, which communicate with the cavity of the 

 abdomen, and through these the blood contained in 

 the latter can enter into the heart. Each of these 

 openings has within it a little valve, in the form of a 

 half circle, which shuts up the passage during every 

 contraction. 



" From this brief detail, it may be conceived, that 

 when the chamber nearest the vent is dilated, the 

 blood in the cavity of the abdomen will enter through 

 the two openings ( l ) above described. When this 

 chamber contracts, the blood which it contains, not 

 being able to return into the cavity of the abdomen, 

 shuts the valve( 2 ), and passes into the second chamber. 

 This dilates for the reception of the blood, and at the 

 same time it receives a certain quantity of blood by 

 its proper openings. Then, by the contraction of this 

 second chamber, the blood passes in the same manner 

 into the third, which receives it equally by the side 

 openings. In this way the blood is propelled from 

 one chamber to another, till it reaches the artery ; 

 and it is the successive contractions of the several 



(1) In Latin, Auriculo-ventricularia. 

 (2).In Latin, Valvula intcrventricularia. 



