390 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
formed from a strand of cells united in a kind of syncytium, and 
traversing the lumen with a complex series of bridges and strands. 
At tho boundary between scolex and bladder the canal in question is 
doubled, but it could not be followed up into the scolex, where perhaps 
the riddle of its nature may be solved. That it is not part of the excre- 
tory system seems the only certainty. The paper ends with a discussion 
of the excretory system in other Cestodes. 
Musculature and Sensory Cells of Trematodes.* — Dr. H. Bettendorf 
has investigated Distomum hepaticum L., D. cylindraceum Zed., D. crys- 
tallinum Hud., D. clavigerum Rud., Diplodiscus subclavatus Goeze, and 
Polystomum integer rimum Frol., and various young stages of Trematodes, 
with particular reference to the musculature and sensory cells. He 
used Golgi’s chrome-silver method and Ehrlich’s methylen-blue method. 
His main results are the following: — 
(1) The muscles of Trematodes retain very markedly their cellular 
character, the contractile elements remaining in connection with the 
large nucleated formative elements or myoblasts. The latter are either 
in direct contact with the fibres, or are united to them by plasmic pro- 
cesses. Thus transitions from the Nematoid to the Annulate type are 
in evidence. The innervation of the muscles is partly through the 
myoblasts, partly by direct connection with the fibres. 
(2) The whole body of the Trematode is surrounded by a richly 
ramified nervous plexus, which lies directly beneath the peripheral 
muscles. The nerve-fibres which arise from this plexus, as also from 
the longitudinal nerves and the annular commissures connecting them, 
pass either to the musculature (motor fibres) or to specific sense-cells 
(sensory fibres). These sense-cells, which have terminal vesicles in 
the cuticula, are distributed over the whole body, but are most numerous 
in the suckers. 
Epithelium of Triclads.j — Dr. R. Jander has studied the peculiar 
state of the epithelium in Dindrocoelum lacteum Orst., D. punctatum 
Pallas, Planaria polychroa 0. Selim., Polycelis nigra 0. F. Miill., Gunda 
ulvse Orst., &c. He describes the structure of the pharyngeal lining 
and its connection with the other tissues of the pharynx, the modifica- 
tion of the simple epithelial cells of the completed embryonic pharynx 
into the peculiar lining found in the adult, and the new formation of 
the pharyngeal lining after injuries. 
llis most important result is that tho pharynx in Triclads (and 
Polyclads as well) is lined by a genuine epithelium of ciliated cells, 
which have by no means lost their cellular character, though they are 
much modified. The cells which line the completed pharynx in the 
embryo persist in the adult, but they are divided into (a) a part which 
serves mainly to protect the pharynx, viz. the ciliated plate, and (h) 
a part which sustains the cell-life, viz. the deep-growing nucleated 
process. Many analogous differentiations are known in epithelial cells, 
and the author suggests the application of his results to other Platyhel- 
minthes. 
* Zool. Jahrb. (Abtli. Anal.), x. (1897) pp. 307-58 (5 pis., 1 fig.), 
t Tom. cit., pp. 157-201 (3 pis.). 
