INTERNAL ANATOMY OF INSECTS. 85 
judgement. No one will deny that the argument from 
analogy is strongly in favour of the old theory: I shall 
not therefore dwell upon it, but proceed to others. Swam- 
merdam, to whose exactness in observing, and scrupulous 
accuracy, every reader of his immortal work will bear 
testimony, expressly asserts that he has seen vessels is- 
suing from the dorsal vessel in the silk-worm, and even 
succeeded in injecting them with a coloured fluid?. New 
it seems extremely improbable that so practised and ex- 
pert an anatomist should have been deceived, especially 
upon a point which would naturally excite his most earn- 
est and undivided attention. Without this recorded ex- 
periment, perhaps, it might be thought, though this was 
very unlikely, that he had mistaken bronchie for veins 
and arteries: but how could they have been i1yected from 
the supposed heart? Another great physiologist, Reau- 
mur, in the caterpillar of the saw-fly of the rose (Hylo- 
toma Rose, Lat.) observed, besides the dorsal vessel, a: 
ventral one of similar form, in which also was a pulsa- 
tion, but slower than that of the other. This he sup- 
poses may be the principal trunk of the veins”. Bonnet 
thought he discovered a similar vessel in a large cater- 
pillar, but with all his attention could perceive no mo- 
tion in it®. Reaumur also, thought he perceived in the 
a His words are—“ In silk-worms I have clearly seen various small 
vessels spring from and approaching to the heart, which I have even 
filled with a coloured liquid. But whether they were veins or ar- 
teries I cannot yet affirm.” i. 112. a.176.a. According to Cuvier 
(Anat. Comp. iv. 418), but I cannot find the passage, Swammerdam 
also mentions having seen a red fluid issue from small vessels in grass- 
hoppers. > Reaum. v. 103. 
© Bonnet ii. 309. Perhaps in both cases the alimentary canal was 
the organ seen. 
