HIRUDO. 37 
power, though it does not drop as readily off branches, stones, or other 
substances on exposure to the air. 
It feeds on the vegetable matter among which it dwells, and it like- 
wise consumes fish. 
Having accidentally committed a quantity of decaying leaves to a 
vessel containing eight or ten specimens, I saw them four or five hours 
afterwards on the side, with beautiful vivid red matter filling the inte- 
ranea, thus shewing the minute differences between the formation of 
these organs, and those of the Hirudo complanata, while corresponding 
in general arrangements. When compared with the animal itself, and con- 
trasting their own peculiar conformation and colour, they proved among 
the most interesting appendages of animation. 
‘In prosecuting my enquiries into the history of those creatures, I 
availed myself of certain facilities offered by a decaying boat which lay 
on the margin of a pond, and served as a receptacle for the leaves of 
trees on the progress of autumn. 
Here the leaves macerating in the rain water, afforded a nidus for 
numerous larve of the musquito tribe wherein to undergo their meta- 
morphoses. I was now in a condition to ascertain that one of these animals, 
of the brightest vermilion colour, was the natural prey of the leech. Yet 
none of the larvee were in the pond, nor any of the leeches in the boat. 
When the prey is introduced to vessels containing the leeches, they 
raised themselves on the sucker, as if surveying around ; then some one 
bolder than the rest advanced, endeavouring to affix itself to the victim, 
which having effected, the position is pertinaciously maintained in spite 
of its writhing and struggles. Should such an attack occur at night, 
an empty brown, transparent skin, scarcely visible, is all that remains 
of the prey in the morning, while the intestines of its enemies are 
seen replete with the red substance that constituted the body. It is 
singular how the fleshy matter of the prey is extracted, while the inte- 
gument is left quite entire. 
Besides repletion with the red larva, the viscera of the leech is often 
full of a darkish substance, either animal or vegetable, for it possibly con- 
sumes the softer portions of decaying plants. But the naturalist will 
