258 CLASS viii. 



Coleoptera the entire stomach (ventricule chylifique DlTFOUii) is beset 

 with numberless conical or filiform saccules, giving a flocculent 

 aspect to its external surface. It may be, that these parts, whose 

 office was formerly supposed erroneously to be the absorption of 

 nutrient fluid from the intestine, prepare the bile : but it seems 

 more probable that they serve to separate the gastric juice 1 . 



The Heart of Insects has the form of a long vessel that 

 terminates behind by a blind extremity and lies above the intes- 

 tinal canal on the dorsal surface. This dorsal vessel becomes 

 narrower forwards, after it has curved slightly downwards. The 

 smaller part may be considered to be an artery, whilst the wider 

 posterior portion answers more closely to the heart of other crea- 

 tures. In this posterior part are different lateral openings, mostly 

 eight or nine pairs : and in front of each opening is a valve formed 

 by a duplicature inwards of the wall. In the diastole of the heart 

 the blood flows into it between two sets of valves, of which the 

 posterior pair come into apposition, whilst the anterior lie folded 

 against the wall and so permit the onward motion of the blood. 

 Systole and diastole succeed each other alternately, moving along 

 the length of the dorsal vessel from behind forwards. SWAMMER- 

 DAM long ago, and STRAUS in more recent times noticed in the 

 dorsal vessel longitudinal and transverse muscular fibres, the latter 

 forming the innermost layer. Surrounding the heart is a space which 

 some writers consider to be a sinus venosus; it is covered by lateral 

 muscles, flat, and of triangular form, which have their broad base 

 towards the heart and fix it in its position (les ailes du Cceur o: 

 LYONET). From behind, the blood flows through the lateraj 

 openings into the heart, and moves forwards ; from before, it flow; \ 

 from the aorta between the organs, especially along the course o i 



organs. Mim. prtsentes, vn. p. 302. In Leucopsis also amongst the ffymenoptera tw 

 such blind saccules are met with ; LEON DDFOUR, ibid. p. 524. 



1 The great uncertainty which prevails concerning the interpretation of tl 

 secretory organs in the lower animals, is a necessary consequence of the fact that tl 

 selfsame secretion, as we learn from comparative anatomy, may be effected by ve} 

 differently formed glands ; see ,T. MUELLER'S Handb. der PhysioL, n. Buch, Abschn. 

 (l. Bd., s. 457, 3fte Aufi.) Chemical investigation alone can here afford light, ai 

 a beginning of the enquiry has been made in invertebrate animals in these last yea) 

 C. SCHMIDT'S _ Investigations: Zur vergleichenden Physiologie der wirbdlosen Thic'. 

 Braunschweig, 1835, deserve, therefore, our thanks, and make us hope for further co 

 munications. 



