ON ANNELIDA. 
75 
excavate their habitations to find in the detritus of the materials 
which they swallow the substance which is to support them. 
We know very little concerning the mode of reproduction 
in the majority of the chetopoda ; it is in fact extremely diffi- 
cult to make direct observations upon them in the bosom of 
the waters, and often in the soil itself which they inhabit ; and 
it is not less difficult to institute experiments for the purpose 
of ascertaining any information on the subject. 
We do not know whether all the species have need or not 
of the approximation of two individuals to propagate their 
species, as is certainly the case with the lumbrici. 
It is only certain, that towards the commencement of 
spring, in our seas at least, we find the bodies of these 
animals filled with eggs, or with a milky, and as it were sper- 
matic matter. In South America, we know from Darfel, 
quoted by Pallas, that the amphitrites at Curatjoa are in full 
vigour in the months of September and October; that at these 
times they deposit their eggs, and that the young ones come 
forth in the month of November. 
The number of the young is immense ; but are they de- 
posited in the egg state or in that of the living animal, or in 
particular localities ? These are facts of which we know 
nothing, and we are likely very long to remain in such 
ignorance. 
The species which live in tubes are certainly not born with 
one, as is always the case, on the contrary, with the conchy- 
liferous mollusca, because with the latter the shell in reality 
forms a part of their skin, which is not the case with the 
tubicolous chetopods. It is then probable that the very young 
chetopod has no tube, but that it forms one immediately 
after it has been expelled from the bosom of the mother. 
We have still less information respecting the duration of 
life in these animals ; we even know nothing in this respect 
about the earth-worms, which we find in such abundance in 
