INTERNAL ANATOMY OF INSECTS. 99 
Iteaum.), which laps over ami defends all the viscera of 
the animal, and goes principally to the formation of the 
imago a . I have said that Cuvier conceives nutrition in 
insects to take place by imbibition or immediate absorp- 
tion ; that is, I suppose, the different parts and organs 
thus constantly bathed in the blood, imbibe from it the 
particles necessary for their constant accretion. M. Cha- 
brier seems to think that it is the compression and di- 
latation of the trunk that duly distributes the nutritive 
fluid b ; Lyonet compares the nutrition of insects by 
their fibres from this fluid, when formed into the cor/75 
graisscux, to that of plants that draw their support by 
their roots from the earth c . Much obscurity, however, 
at present rests upon this subject — much for future 
investigation to explore ; but in all the works of the 
Most High there is always something inscrutable, 
something beyond the reach of our senses and facul- 
ties, which teaches us humbly to adore his infinite per- 
fections. 
II. The circulation of the AracJmida is next to be 
considered ; and the term applied to these becomes 
strictly proper. Two great tribes, in our view of the 
subject, constitute this Class, — the spiders (AraneidecC) 
and scorpions {Scorpionidea) : I shall give you some ac- 
count of the circulating vessels of each. — In spiders, the 
heart in general is a long dorsal vessel as in insects, but 
supposed to be confined to the abdomen, growing slen- 
derer towards each extremity, particularly the anal. In 
some also, as in Aranca domestica, like that of insects, it 
has lateral muscular appendages ; but in others, as in 
a Cuv. Anat. Comji. iv. 158. Herold Schmetterl 28. 
b Sur le Vol des Lis. c. iv. 88. note 1. c Anat. 428. 
H 2 
