258 CLASS VIII. 
Coleoptera the entire stomach (ventricule chylifique Durour) 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’. 
The Heart of Insects has the form of a long vessel that 
terminates behind by a blind extremity and lies above the imtes- 
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 s¢nus venosus; it is covered by lateral 
muscles, flat, and of triangular form, which have their broad base 
towards the heart and fix it im its position (les ailes du Cour of 
Lyonet). From behind, the blood flows through the lateral 
openings into the heart, and moves forwards; from before, it flows 
from the aorta between the organs, especially along the course of 
organs. Mém. présentés. vi. p. 302. In Leucopsis also amongst the Hymenoptera two 
such blind saccules are met with ; Lion Durovur, ibid. p. 524. 
1 The great uncertainty which prevails concerning the interpretation of the 
secretory organs in the lower animals, is a necessary consequence of the fact that the 
selfsame secretion, as we learn from comparative anatomy, may be effected by very 
differently formed glands ; see J. MUELLER’s Handb. der Physiol., u. Buch, Abschn. 2 
(1. Bd., s. 457, 3¢te Aufl.) Chemical investigation alone can here afford light, and 
a beginning of the enquiry has been made in invertebrate animals in these last years. 
C. Scumipt's Investigations: Zur vergleichenden Physiologie der wirbellosen Thiere, 
Braunschweig, 1833, deserve, therefore, our thanks, and make us hope for further com- 
munications. 
