3 1 8 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cells. There is a single testis ; the oviduct resembles that of Aspidogaster 

 near the ovary in having the sume "tuba fallopii ;" there is n<> distinct 

 ootype or shell gland, and no Laurer canal. 



Incertae Sedis. 



Excretory Apparatus in Entoprocta.*— G. Stiasny has observed 

 various details of this in the living specimens of Pedkellina echinata and 

 Loxosoma annelidicola, as well as sections of these and other types. In 

 P. re hi n (tttt- the excretory apparatus consists of an unpaired duct which 

 divides into two branches, forming an inverted Y- It lies between the 

 oesophagus and nerve ganglion. The blind ends of the fork are closed 

 by an end cell, which appears like a massing of plasma with a large 

 nucleus. The wall of this canal contains two or more cells with large 

 nuclei ; the lumen is wide, the cells are very long and narrow and with- 

 out cilia, except the end cell, which has a very large " flame." There 

 are cilia on the unpaired portion of the system. It is probable that, 

 contrary to the finding of Prouho, the excretory apparatus of the 

 Entoprocta is of one type. 



Rotifera. 



New Rotifers from Scotland.f — James Murray, in studying the 

 fauna of Scotch lakes in connection with the Lake Survey under the 

 Pullar Trust, has found the following twelve new species of' Rotifers of 

 the order Bdelloida, which he describes very fully, with seven plates of 

 illustrations : Gallidina aiujusticolUs, G. annulate, G. crenata, G. pukhra, 

 G. muricata, C. crucicornis, G. armata, G. incrassata, Philodina laticornis, 

 Ph. laticeps, Ph. humerosa, and Microdina paradoxa. The last-named 

 forms a new genus and a new family, Microdinadte, characterised by 

 the absence of a corona, and by jaws intermediate between the ramate 

 type of all other Bdelloida, and the malleo-ramate type of Melicertz. 



Echinoderma. 



Artificial Production of Vitelline Membrane in Unfertilised Ova 

 of Sea Urchin. :[— Curt Herbst finds that traces of silver salts in the 

 water evoke the formation of vitelline membranes on unfertilised ova, as 

 also happens under the influence of chloroform, clove-oil, xylol, and other 

 reagents. The formation and elevation of the vitelline membrane is not 

 a simple coagulation process. The elevation of the membrane from the 

 surface of the egg is first of all due to a vital change in the cytoplasm, 

 which retracts from the primary vitelline membrane and secretes a sub- 

 stance between that and itself. When water enters the interspace the 

 primary limiting membrane is raised mechanically. Apart from this, 

 however, there is the modification of the readily penetrable primary 

 membrane into a more resistent secondary envelope. This change may 

 be a coagulation or similar process. In any case it can be induced in 

 unfertilised ova by coagulating reagents which do not rapidly kill them. 

 It follows that in normal conditions, the spermatozoon must contain a 



* Arbeit. Zool. Inst. Wien, xv. (1904) pp. lS:S-f>(J (1 pi.). 

 t Trans. Roy. Soc. E<lin., xli. (1905) pp. 3G7-SG (7 pis.). 

 X MT. Zool. Stat. Neapbl, xvi. (1904) pp. 445-57. 



