14 DR. F, E. BEDDARD ON 
the developing asexual worm which arises, as I suppose, directly 
from the egg. There is, however, clearly a general resemblance 
to the latter, and, as I think, an important resemblance. 
The cavities also contain in both the immature Cestodes now 
under consideration a coagulable fluid apparent on staining. The 
tubes of the water-vascular system are much alike in the two 
worms. In both the dorsal vessel is the smaller and has a thick 
muscular wall; while the two worms also show resemblance 
in the fact that the transverse vessels which run across the 
segments arise by two origins from the larger ventral vessel. 
This detailed likeness is very striking. In spite of these points 
of likeness there are numerous points of difference between the 
two species. Cysticercus fasciolaris would seem to show no such 
specialisation of the bladder-cavities, or at any rate no such 
variation of structure in the cavities found in its interior, as 
does Urocystidium. The total absence of hooks, and indeed of a 
well-marked scolex, in Urocystidiwm has been already commented 
upon. The Cysticercus under consideration agrees with other 
Oysticerct in differing absolutely from Uvocystidiwm in these 
features. Dr. Bartels heads one section * of his memoir upon 
Cysticercus fasciolaris as follows:—‘t In welcher Beziehung 
stehen Cysticercus fasciolaris und Tenia crassicollis za eimander 
betreffs der Hohe ihrer Organisation ?” The same query might 
well be asked concerning Uvrocystidium. In the former case 
the only differences are in the disappearance of the traces of 
the bladder, the appearance of the gonads, and, apparently, the 
slight inevease of the number of hooks upon the scolex. The 
general level of organisation is upon precisely the same level 
in the two stages of development. The latter statement can 
well be made of Urocystidiwm. Transverse sections of the sexual 
adult and the completely developed immature stage, which are 
shown in my earlier paper upon this worm, leave little structural 
difference between the two forms save the two features in which 
the. Cysticercus differs from its Tenia. The only important 
addition to be made is of course the absence of a scolex in 
the young Urocystidiwum. 1t was, in fact, not merely the 
equahity of organisation but also the details of likeness which 
led me to assume originally that the one form of Urocystidiwm 
was really a stage in the development of the other. So far 
aso 1s known, these two forms are the only ones among the 
higher Cestodes in which there is a high grade of organisation 
in the ‘sexless stage. And it is perhaps this general fact of 
likeness which tends to impress upon one the further points 
of likeness between this form and Cysticercus fasciolaris, and 
to diminish the really important points of difference already 
referred to. As to further development, Bartels is of opinion 
that the Cysticercus develops into the Zenia with no further 
change than the loss of the bladder. 
* Toe. oe p. 542. 
