54 
SUMMARY OF CURRENT RESEARCHES RELATING- TO 
part of the sixth segment, against the muscular layer, in a dorsal 
position. Each funnel has a thin tube which passes through the 
muscular coat, but instead of opening directly and freely on the 
epidermic surface, it opens into a longitudinal duct. This duct may 
remain at certain places an epithelial groove, or it may be a complete 
tube. As Owenia is somewhat tight within its tube, the duct serves for 
the escape of the ova. It is of interest to compare it with the longitu- 
dinal duct of Lanice conchilega , described by Cunningham and E. Meyer, 
which, like that of Polymnia , Polygordius , and others has been compared 
with the segmental duct. 
Filiform G-lands of Owenia fusiformis.* — Prof. G. Gilson takes the 
filiform glands of this tubicolous Polychmte as the text for the second of 
his researches on secreting cells. Their structure, general and minute, 
is described in detail, and it is urged that the substance which fills the 
glandular tubes is got rid of by the epithelial cells in the same way 
as the silk or sericigenous substance is got rid of in Lepidoptera and 
Trichoptera ; that is by a process of regular oozing through the cellular 
membrane. 
Comparative Anatomy of Oligochseta.t — Dr. R. Hesse begins with 
a description of the musculature. In Chsetogoster , Nais, Tubifex , 
Lumbriculus , &c., the longitudinal muscle-cells are of a nematoid type, 
U-shaped, with a contractile sheath surrounding the unmodified plasma, 
except at the narrow end turned towards the middle of the body. In 
the annular muscles, as seen in horizontal longitudinal section, the 
same nematoid type occurs, but the plasma is prolonged far beyond the 
contractile sheath. These prolongations bear the nuclei and are all 
disposed in two lateral lines. The same nematoid type occurs in all 
Lumbricidae, though there are often modifications ; thus in the majority 
of the cells which form the longitudinal bundles there is no unmodified 
plasma between the limbs of the U, but only at the open end. The 
unmodified plasmic portion bearing the nucleus represents in position 
the embryonic cell ; physiologically it is probably the part which 
transmits the nervous stimulus to the contractile substance. Herr Hesse 
goes on to show in regard to the disposition of the longitudinal muscles 
in Lumbricidae, that these forms pass through stages which are fixed 
states in the Limicolae and Polycbaeta. 
His second chapter is concerned with the integumentary sense- 
organs of Lumbricidae. The most important result is that there is a 
regular arrangement of sensory organs — groups of sensory and support- 
ing cells — occurring on three zones around each segment, in relation to 
the three pairs of annular nerves which arise from the nerve-cord in each 
segment. They are extraordinarily abundant on the upper lip, which is 
an important tactile organ. Physiologically, as they seem to respond to 
diverse stimuli, they may be regarded as Uebergangssinnesorgane (Ranke) 
or Wechselsinnesorgane (Nagel). 
The third chapter deals with the gonads of Lumbricus , &c. Here 
there is much that is interesting. Thus the ovaries show three zones — 
(a) germinal cells, (b) a zone of multiplication, (c) ova. The ova show 
* La Cellule, x. (1894) pp. 299-331 (1 pi.). 
f Zeitschr. f. wiss. Zool., lviii. (1894) pp. 394-439 (2 pis,, 3 figs.). 
