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in each, cephalic bundle, and sixteen in each abdominal 
bundle. This is a very striking and curious change, and is 
in harmony with the numerous facts which establish a direct 
nutritional relation between the genitalia and tegumentaxy 
structures, e.g. puberty, the stag’s horn and testicle, the plumage 
of birds, colours offish, &c. The sexual form also possesses a 
well-marked cuticle (PI. XIV, fig. 6), which is l'epresented by 
the merest pellicle in the asexual condition. I have observed 
certain appearances, which make me think it possible that 
the Chcetogaster Limncei sheds parts of its skin and bristles 
during the development of the genitalia; for amongst the 
specimens I examined in October were very many with a less 1 
number of bristles than is normal to the asexual forms. In 
these individuals the genitalia were not yet traceable ; but 
some had only six cephalic bristles in one bundle and seven in 
the other, in the place of twelve, which is the almost invariable 
number at other seasons of the year ; the abdominal bristles 
were equally diminished, giving the idea that they had 
fallen out, or been lost in some way. The most curious 
thing, however, is that in all these cases and in the sexually 
mature individuals, too, numbers of bristles could be seen 
occupying the stomach and intestine, undoubtedly swallowed 
by the Chsetogaster. It appeared to me probable that the 
worm had swallowed its own shed bristles and cuticle ; but 
it is possible that the presence of bristles in the stomach may 
have been due to other worms having been swallowed — the 
smaller by the larger individuals. 2 This seems unlikely, because 
at no other time of the year have I seen these bristles in the ali- 
mentary canal of Ch. Limncei, though I have observed them 
for a long time. I am inclined to believe that there is a 
shedding of old, as there is certainly a production of new, 
bristles. Another change with regard to the bristles is in 
the equality of length of the cephalic and abdominal bristles ; 
whilst in the asexual form the cephalic bristles are about 
-g4o-th of an inch, and the abdominal about th of an inch, 
in the sexual form both abdominal and cephalic bristles are 
much larger, in accordance with the greater size of the worm, 
and are more nearly of an equal length, the cephalic bristles 
measuring more than —i— th of an inch in length. I am also 
1 There is frequently considerable variation in the number of bristles in a 
fasciculus in the same species among Oligochseta. Thus, in Enchytraeus, as 
remarked by Henle, and in Lumbriculus, Clitellio, &c., as I have observed, 
to the extent of four in place of seven, or vice versa. 
2 Possibly the sexual zooid on becoming detached from its parent zooid 
swallows it, since the latter is much the smaller. The growth of the sexual 
zooid has yet to be observed. 
