18 On the Encystment of AXolosoma. 
that all the cocoons, each furnished with its one ovum, were 
fabricated either upon the same day or at the exact intervals 
that would allow of the embryos simultaneously reaching 
their full term of development. This supposition is rather 
too much to believe. S‘ourthly, the supposed cocoons possess 
no apparatus of fixation ; this is not a positive bar to believing 
them to be cocoons, for some worms have not any such 
mechanism, but in others the cocoon is enveloped in a gelati- 
nous layer which causes it to adhere firmly to the surface 
upon which it falls. J7fthly, and, if my observations are correct, 
this is an absolute and final objection to regarding the cysts 
of Aolosoma as cocoons. I treated a number of these bodies 
with strong potash; the first effect of this reagent was to 
change the “colour of the pigment to a splendid violet, which 
rapidly disappeared. This fact I have already recorded in 
this Journal*, ‘The second effect was to colour bright green 
the contents (be it noted that there were contents) of the ali- 
mentary canal. -dolosoma is a vegetable feeder, and potash 
produces a precisely similar effect upon the colouring sub- 
stances of various alee. ‘The natural inference is that the 
supposed embryos had been feeding upon such alge; clearly 
therefore they cannot be embryos at all, as algze could not 
gain access to the interior of the cysts. They must have fed 
upon these alge and then eneysted themselves. It is perhaps 
unnecessary to state that the worms within the cysts had 
sete precisely similar to those crawling about outside. I 
mention this fact, however, more p varticularly since Maggi did 
not find sete upon the worms within the cysts described by 
him. ‘The sete might, however, be passed over; they are 
extremely delicate, and the position of the worm in the cyst 
—coiled upon itself{—is not by any means a favourable one 
for allowing these structures to be seen. 
Considering all these facts it seems to me necessary to 
arrive at the conclusion that olosoma can temporarily encyst 
atsclf, after the fashion of some of the lower organisms. It 
should be noted that the alimentary tracts of the free-swimming 
individuals did not for the most part contain much food; and 
I saw but little evidence of active feeding on the part of the 
worms in the shape of the very characteristic pellets of dung 
evacuated by these Annelids. ‘This cessation of feeding may 
be preliminary to encystment; the torpor caused by the 
approach of winter may have brought about a general cessa- 
tion of activity, which culminates in encystment for a period 
_ * “Notes upon certain Species of Aolosoma,” Ann. & Mag. Nat. Hist. 
Oct. 189. 
