480 
VERMES. 
subdivisions of the two series, “ true parasites ” and “commensals,” which he 
had previously proposed. He also figures and describes a number of new 
and little-known cestoid and other parasitic worms found in fish occurring 
on the Belgian coast. 
16. Knock replies to a question raised by the French Academy in award- 
ing honourable mention to his work on the Natural History of the Broad 
Tape- worm (1863), viz. Does the embryo of this worm develop directly into 
the adult Bothriocephalus, or does it undergo other metamorphoses in order 
to reach this last condition? In spite of the facts contained in Knock’s 
memoir, Leuckart, Bertolus, and others supposed that fish were intermediary 
in bringing the worm to man, an hydatid form possibly developing, as in the 
case of Tcenia and its Cysticercus. Knoch proves, by feeding a young dog, 
that the Bothriocephalus latus develops direcl from the ciliated six-hooked 
embryo. He had previously endeavoured, with negative results, to obtain an 
hydatid form by feeding fish with the embryos. 
17. (a) The development of Ligula and Tricenophorus^ (6) Tcenia malleus^ 
Goeze, (c) Distoma caudate of Budolphi, are the subjects of these notes, 
18. Metschnikoff considers that the formation of the daughter and of 
the so-called grand-daughter proceeds from the common mass of completely 
identical embryonal cells, which divide into a peripheral part, which be- 
comes the daughter, and a central part, giving rise to the so-called grand- 
daughter. He discusses the homologies of various larval Trematoid and 
Cestoid forms. 
19. Philippi, writing from Santiago, describes and figures (not in great 
detail) the very cmdous leech, bearing five long tentacles or digitations at its 
cephalic extremity, to which Blanchard gave the name Temnocephala chi- 
lensis. Its exact habitat was not previously known. Philippi finds it on 
the gills and under the tail of the fr eshwater crustacean ^ylea. 
20. Vaillant, in about seventy pages and with two plates, gives an 
account of the viscera of Bontohdclla verrucata. Ho does not treat of the 
histology in detail. 
21. Metschnikoff doscribos various Fchinodoriu-larvu), and also the 
development of the IHlidium-lwawiSi of certain Nemerteans. Up to this time 
the development of the Pilidium from the egg had not been observed. The 
material on which the author began his work was handed over to him by 
Kowalewsky when leaving Messina in April 1868. The embryonal develop- 
ment of the Nemerteans observed by Desor, Max Schultze, and Van Beneden 
did not present the Pi7if/mm-stage j and, indeed, the last author, in a paper on 
“ commensalism,” mentions the young Nemertean in the P/h't/iwwi-larva as a 
case of parasitism. Metschnikoff describes carefully the Nemerteans from 
which he obtained the eggs the subsequent development of which he 
studied, but he does not identify them with any known species. The yelk- 
segmentation in the Nemertean egg was complete, leaving a central seg- 
mentation cavity. The first commencement of the formation of the Nemer- 
tean body in the Pilidium consists in two pairs of inversions of the skin, 
which form not only the worm but the amnion surrounding it. The cavity 
arising fr’om the inversions becomes the amnion-cavity. Two median 
vesicles also form, which later are connected with the lateral vessels of the 
worm. The germ-stripe (Keimstreif) is represented by the four plates thus 
formed, and can be separated into an inner and outer layer (Keimblattern) : 
