ZOOLOGY AND BOTANY, MICROSCOPy, ETC. 
43 
vesicles superficially like the segmented larvae of Diptera. After 
describing the histology of Leucochloridium, Heckert gives an account 
of his experiments in infecting songsters with this parasite. The results 
enabled him to trace the transition from larva to adult. In four days 
after infection the change is complete, and in fourteen days the eggs 
are liberated. The Distomum inhabits the cloaca of the bird, and the 
eggs were frequently observed in the faeces and urinary products. The 
most characteristic peculiarities of the adult are the nature of the head 
end and the position of the genital aperture. The dorsal wall of the 
mouth-sucker is much longer than the ventral, and the aperture is 
sharply inclined to the ventral surface ; both suckers can thus be used 
at once for attachment, which is probably important in such a situation 
as the cloaca. The genital aperture is not ventral, as is usually the 
case, but terminal, or even turned towards the dorsal surface. 
So far as Heckert was able to follow the first stages in the develop- 
ment of the egg, Schauinsland’s account of the embryology of Trematodes 
holds true. After describing various steps in the development, the 
author passes to the ciliated free-swimming embryo. He was able to 
demonstrate that the chemical stimulus of the snail’s digestive secretion 
was of itself sufficient to bring the embryo out of the egg-shell. By 
sections he detected the embryos in process of boring through the wall 
of the gut, and believes that the cilia are lost at this stage. The sporo- 
cysts found in the adjacent organs of the snail begin as small, almost 
spherical bodies, within which a rapid multiplication of cells takes place 
with direct nuclear divisions. The appearance of an internal cavity and 
a distinct germinal epithelium, the liberation of egg-like cells into the 
cavity of the sporocyst, and the curious root-like ramifications noticed 
at the outset are described in detail. It is important to note that it is 
always a single cell in the germinal epithelium of the sporocyst-wall 
which starts a “ germ-ball ” or a fresh individual, so that Leuckart’s 
comparison of “ germ-cell ” and ovum is corroborated. The development 
of the “ germ-balls ” into larvae, and the histological differentiation 
exhibited in the process are, finally, described. 
Position of Excretory Pores in Ectoparasitic Trematoda.* — Dr. M. 
Braun who has been surprised at the variations in the statements affect- 
ing the position of the excretory pore in ectoparasitic Trematodes, some 
authors saying it is ventral and others dorsal, has made an investigation 
by the method of sections — the only safe one — and found in all forms 
examined that the pores were dorsal in position. 
Larva of Taenia Grimaldii.t— M. E. Moniez gives a description of 
cysts collected from various dolphins in the Atlantic during the voyage 
of the ‘ Hirondelle.’ The other host, or that which contains the adult, 
will probably prove to be Orca or a Dolphin, as these animals are 
cannibal in their habits. The youngest stage observed presents the 
appearance of an ordinary Cysticercus ; in older individuals the rudiment 
of the body of the future Tsenia, considerably elongated, was seen. It 
had the form of a tube hollow from end to end, and its cavity communi- 
cates with the exterior by the orifice of the cysticercus. In still older 
* Zool. Anzeig., xn. (1880) pp. 620-2, 
t Comptes Kendiis, cix. (1889) pp. 825-7. 
