443 
in the services of still another worm for each — since Darwin’s 
work teaches us that it would be the merest chance if, after the time 
that elapses between copulation and oviposition, the same worms were 
united again. Hence a second coition is rendered extremely impro- 
bable, whilst it certainly is not necessary to explain the phenomena. 
Therefore it seems to me that this generally accepted explanation must 
be almost entirely abandoned. 
The formation of the cocoon must of course be a matter for ob- 
servation, and as such I can add nothing to the little already known. 
Some general observations, however, may be of service. First, I have 
difficulty in believing that the clitellum secretes the cocoon, for these 
reasons: 1) That, on this assumption, its position, 17 segments behind 
any trace of reproductive organs, is mexplicable. It is not sufficient 
to say that my own diagram clears this up by illustrating its important 
functions in copulation — that would savour of the mountain coming 
to the prophet. For if the clitellum were say 10 segments for the for- 
ward, it would still answer all the purposes of copulation, and undoub- 
tedly gain in the secretion of the cocoon. I think that, considering pro- 
babilities, it must be admitted that the position of the clitellum points 
to the conclusion that its only office is to meet the exigencies of an 
otherwise difficult copulation. ‘To effect this, it was necessary that it 
should be somewhere behind the genital organs, in fact in much 
about the same position that we find it now; but if it had been inten- 
ded to have performed the double function, then we should have ex- 
pected it to have been nearer the reproductive organs, and not to have 
lost more than it gained by being farther back. 2) That if the cli- 
tellum does secrete the cocoon, then it is only slightly developed, and 
sometimes its characteristic features are altogether wanting, in preci- 
sely that part where it should be most highly developed — in the ven- 
tral region. That therefore the cocoon should have an uneven texture. 
3) It would be necessary to explain how it was peeled off over 32 seg- 
ments, and against the resistance of the setae, and how the ends were 
closed up.. 4) With reference to the former, I may say that it is sup- 
posed to be worked off by longitudinal contractions of the body , and 
to the latter that the ends are believed to be twisted and not sealed. 
But if the clitellum does not secrete the cocoon, we must consider 
what does. My belief is, although I am not yet in a position to establish 
it, that the capsulo-genous glands do this work. Their position toa 
great extent suggests this function, and if they extended to the 14th 
segment, there would be strong a priori grounds in favour of the as- 
sumption. My idea of the process is this: after copulation (how long?) 
the glands secrete a cuticular sheet of mucus, in which calcium salts 
