394 
8UHMARY OF CURRENT RESEARCHES RELATING TO 
The blood of S. nudus also shows corpuscles with haemerythriu 
(usually sj>herical, but not constant in form) which multiply by nuclear 
budding. The tliird component elements are the leucocytes, of two sorts ; 
and besides these there are large round transparent discs, both unicellular 
and multicellular. Ciliated infusorians and genital cells also occur in 
the blood. 
The urns are seen seated inside the vessels on the walls of which 
they arise. It is probable, however, that they also arise elsewhere, for 
they are found freely in the body-cavity, with which the vascular system 
is not in any communication save by very minute openings between the 
walls of the epithelial cells. The leucocytes seem to arise in a special 
gland in the wall of one of the blood-vessels. The genital cells pass 
through three stages in the gonads at the base of the ventral retractors 
before they are liberated into the blood. 
Metalnikoff believes that the special function of the “ urns ” resembles 
that of phagocytes, but on a larger scale. They serve to protect the 
organisms from hard substances (sand particles, &c.) which may get into 
the body-cavity if the gut be ruptured. It may also be, as Cuenot and 
others have suggested, that their quick movements do something to com- 
pensate for the absence of a heart. As to excretion, injected ammoniacal 
carmine is engulfed by the leucocytes and urns, while indigo-carmine 
and fuchsin are excreted by the segmental organs. It is interesting to 
note that in Annelids generally indigo-carmine is not got rid of by the 
nepliridia, but by the chloragogen cells. 
Forgotten Echiuroid.* — Mr. H. Lyster Jameson describes Holo- 
thuridium papillosum, which should be called Thalassema papillosum 
Delle Chiaje. It was discovered by Delle Chiaje, and has been twice 
dredged at Naples. It occupies a position nearer to Thalassema dia- 
phanes than to any other known species, but seems to be quite distinct. 
Rotatoria. 
Structure of the Vibratile Tags in Rotifers .y — Mr. John Shephard 
has studied the minute structure of the flame-cells in various Rotifers, 
particularly in Brachionus pala and Euchlanis dilatata , and arrives at the 
conclusion that this organ consists of a flattened funnel, closed at one 
end by a protoplasmic mass, to which is attached an undulating mem- 
brane lying between two thin delicately striated walls, to which it is 
joined on each side for its whole length, being free only at the narrow 
proximal end, and dividing the interior of the tag into two separate 
cavities. The presence of the two long flagella on the outside of the 
tags in Asplanchna amphora , discovered by Mr. C. F. Rousselet, is con- 
firmed. Mr. Shephard considers that the excretory fluids pass by osmosis 
through the thin walls of the tags. 
N ematohelminth.es. 
Anatomy and Biology of Oxyuris curvula.J — Herr Hermann Ehlers 
has studied in detail this hitherto little-known parasite. It occurs in 
* MT. Zool. Stat. Neapel, xiii. (1899) pp. 433-9. 
f Proc. Roy. Soc, Victoria, xi. pt. ii. (1898) pp. 130-6 (2 pis.), 
j Arch. Naturgeschichte, lxvi. (1899) pp. 1-26 (2 pis.). 
