80 OF THE SENSES OF 
He observed them in the small Nettle Tortoise-shell 
Butterfly ; but he was unable to trace their termi- 
nation ; and cautiously observes, “ What the office 
of these vessels is, and whether they may not be 
salivary ducts, I cannot take upon me to deter- 
mine.”* That naturalist, as well as Ramdohr, was 
inclined to suppose these the silk reservoirs ; but 
that they were not was proved by Lyonnet, who 
detected a conspicuous pair of salivary ducts in the 
larva of the Goat Moth ;t and in his investigations, 
he is borne out by the dissections which were after- 
wards made by Heroldt, in his minute and satis- 
factory anatomy of the Cabbage Butterfly. 
Butterflies, in their mature state, have but little 
fluid matter in them; and, besides, being so much 
exposed to the scorching rays of the sun, in which 
they are continually sporting, are liable to great 
thirst. They are often, therefore, to be seen in the 
act of drinking by the sides of pools of water ; par- 
ticularly in the sultry autumnal months. Mr 
Rennie says, “ At Compton Basset, in Wiltshire, I 
once counted about fifty of the small White Butterfly 
(Pontia Rape, of Haworth) all assembled within 
a space of a few yards on the sludge which had just 
been left by the water of a pond, partially dried up 
by the sun. What was most remarkable, they 
* Book of Nature, Part ii. p. 21. 
+ Traité Anatomique, p, 112. 
