56 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
Sphincter of Nephridia of Gnathobdellidae.* — Prof. H. Bolsius has 
determined the existence of a nephridial vesicle with an excretory duct 
in nine species of Leeches ; the duct, which is generally of some length, 
always has near its point of union with the vesicle a sphincter-muscle; 
the cells of this sphincter are smaller in diameter than the ordinary 
muscular cells of the body. The terminal portion of the excretory duct 
has no proper musculature. 
Structure of Clepsine.t— Mr. Asajiro Oka has studied the structure 
of various species of Clepsine , of which he found seven around Leipzig. 
He begins his description with the rings and segments, in regard to which 
there is much variety of interpretation, but what follows is more im- 
portant. 
The body-cavity consists mainly of five longitudinal lacunaB — a median 
lacuna, which divides into dorsal and ventral lacunae in the region where 
the gut is pouched, two lateral or marginal lacunae, and a pair of inter- 
mediate lacunae, simple or divided, between the median and the laterals. 
These are all connected by segmental transverse lacunae. There are also 
superficial hypodermic lacunae. The lacunae contain (u) free-swimming 
cells like those in the blood, and (b) larger cells (peculiar to Clepsine ?), 
which are at first fixed to the walls, but subsequently become free and 
divide. Oka calls the lacunae coelomic because they are quite distinct 
from the vascular system, because the nephridia open into them, because 
the gut, female gonads, &c. really lie in the lacuna), and for other 
reasons. 
The vascular system. While corroborating much, Oka notes that the 
dorsal vessel is saccular, and surrounds the gut, that a pair of vessels 
perforate the oesophageal ganglioD, and that the blood-fluid is different 
in colour from the lacunar fluid, which makes the assumption of com- 
munication between the two systems improbable. 
The nephridia. That part of the nephridium which lies between the 
capsule and the skin-invagination consists of a simple row of cells per- 
forated by a canal. Proximally this is branched ; its lumen increases 
towards the external aperture. As long as the canal is branched, the 
cells are glandular ; thereafter, they are merely tubes. The limits be- 
tween adjacent cells mostly disappear, and the row is so coiled that the 
walls of adjacent portions fuse. The glandular and the distal terminal 
parts remain distinct. 
As regards segmentation, body-cavity, vascular system, nephridia, &c., 
Clepsine is finally compared with other Annelids, and the author con- 
cludes that it is among Hirudinea the type nearest the Oligochseta. 
Nemathelminthes. 
Strongylus filaria R.J — Herr 0. Augstein furnishes a careful de- 
scription of this common parasite of sheep, which does not seem to have 
been hitherto investigated in any detail. The worm occurs in the lungs, 
bronchial tubes, and trachea, and is of much practical importance. Of 
* La Cellule, x. (1894) pp. 335-45 (1 pi.). 
t ZeitscLir. f. wise. Zool., lviii. (1894) pp. 77-151 (3 pis.'. 
J Arch. f. Naturges., lx. (1894) pp. 255-304 (2 pis.). 
