486 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
lie combats the view of Ijima that it does not coexist with the canal of 
Laurer. For the present we must be content to regard the organ as one 
sui generis , and consider that its genetic relations are altogether doubtful. 
It must not be supposed to have any very great significance, for it is 
wanting in many ectoparasitic and all endoparasitic Trematoda. 
An account is next given of the anatomy of Octobothrium lanceolatum , 
which was examined after staining in Canada balsam. 0. merlangi, 
which has many points of resemblance to it, is next more shortly de- 
scribed. Polystomum ocellatum , from the pharyngeal cavity of Emys 
europsea , is, lastly, fully described; but here, again, details only are 
given. 
Excretory System of Temnocephala.* — Prof. W. A. Haswell points 
out that the mode of opening of the excretory system of Temnocephala — 
by means of two dorsally and anteriorly placed apertures — is not as rare 
among Trematodes as it was once thought to be. Braun has shown that 
any other mode of opening is exceptional among the Monogenea. The 
excretory system of Temnocephala is, however, remarkable in several 
points ; each of the two excretory openings leads into a thick-walled 
contractile terminal sac, pyriform in shape, with a curved apex. A 
layer of muscular fibres incloses the sac, but the greater part of the 
thickness of the wall is due to a thick layer of finely fibrillated proto- 
plasm. This terminal sac is a perforated cell, with its nucleus situated 
in its narrower posterior portion. The main excretory canals are, there- 
fore, intracellular ; the walls of the entire system, so far as the larger 
trunks are concerned, are composed of a few greatly produced, and 
sometimes branched cells. The main branches give origin to a system 
of canaliculi ; and there are a few ciliary flames. Each main trunk gives 
off a branch which quickly divides into a number of vessels which enter 
the wall of the terminal vesicle and ramify through its substance, giving 
rise to a system of exceedingly fine capillary channels. We have, then, 
this remarkable result, that in the substance of the perforated cell there 
is a richly ramifying system of capillaries containing a number of ciliary 
flames. This arrangement is paralleled by certain of the unicellular 
glands in the same animal, in which a breaking up of the duct into 
a number of channels within the protoplasm is distinctly traceable in 
sections of specimens fixed with Flemming’s solution. 
Distomum folium.j — Prof. M. Braun, doubtful as to some of the 
peculiarities of structure ascribed by Zschokke, has made an indepen- 
dent investigation of this parasite ; he finds that its anatomy is of a more 
normal type, and he recommends the use of serial sections as being the 
mode of investigating the worm with the best results. 
Euryccelum Sluiteri.f — Dr. M. Braun gives reasons for thinking 
that this Distomid, which was discovered by the late Dr. Brock on 
Diacope metallicus , and for which a new genus was made, belongs really 
to Apoblema , from all the known species of which it differs by the great 
width of the collecting spaces of the excretory organs as well as by the 
large size of some of the other parts. 
* Zool. Anzeig.. xv. (1892) pp. 149-51. 
t Centralbl. f. Bakteriol. u. Parasitenk., xi. (1892) pp. 461-3. 
x Tom. cit., pp. 727-9. 
