434 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Nematohelminth.es. 



New Nematodes.* — 0. von Linstow describes new species of Ascaris r 

 Heterahis, Physaloptera, Spiroptera, Filaria, Agamonema, Gordius, and 

 EcMnorltynchus • and also furnishes notes on a number of previously- 

 recorded forms. 



Platyhelminth.es. 



New Rhabdocffll.t — F. F. Laidlaw describes Typhlorhynchus nanus 

 g. et sp. n. living on the body of the Polychset Nephlhys scolopendroid.es. 

 Its affinities are with the Mesostomidae and Proboscidae ; perhaps it may 

 be ranked most conveniently among the latter and in the neighbourhood 

 of Pseudorhynchus. It is the only member of either of the related families 

 that has adopted an epizoic habit. The character of the parenchyma 

 should be specially marked, for in the way it merges into the endoderm 

 it shows a distinct approach to the condition found in the Alloiocoela. 



Notes on a Planarian.* — X. Raspail has made some interesting 

 observations on an undetermined species of Planaria, whose generations 

 he has watched since 1892, in a vessel holding about two litres. He 

 notes their changes of colour — often harmonising with that of the 

 objects on which they live, and due to the fluid in the gastric ramifica- 

 tions. They fed greedily on flies which got entangled on the surface of 

 the water, and on the common earthworm whose presence in the vessel 

 they noticed with extraordinary rapidity, while the introduction of 

 Lumbricu8 foztidus passed unnoticed. They were also seen devouring 

 Gammarus puteanus. 



Distomum duplicatum in Fresh-water Mussels. § — H. Reuss de- 

 scribes the abundant occurrence of sporocysts and cercariae of this Trema- 

 tode inside Anodonta mutabilis CI ess. var. cellensis. The sporocysts filled 

 up the space between the coils of the gut and the gonads ; they were seen as 

 shining white spots through the epidermis of the foot ; some occurred on 

 the mantle and in the pericardium. The liberation of the cercariae from 

 the exbalant aperture and the changes which followed in the water are 

 described, but the life-history was not discovered. 



Maturation and Fertilisation in Distomum hepaticum.|[ — L. F. 

 Henneguy briefly describes the appearance of the immature ovum and 

 the vitelline cells which surround it. He notes the interesting fact that 

 many spermatozoa are absorbed, and probably digested, by the vitelline 

 cells. 



After the entrance of the spermatozoon, and before its transforma- 

 tion into a male pronucleus, the seminal vesicle loses its contour ; in 

 its place there appears a maturation spindle with two punctiform 

 centroeomes at each end ; the chromosomes — few in number and very 

 unequal in size — are irregularly distributed in the equatorial region. 



Two bodies like polar bodies were seen, but their actual expulsion 

 was not observed. The oocyte remains with male and female pronuclei 

 quiescent and independent until the liberation of the egg. 



* Arch. Mikr. Anal, lx. (1902) pp. 217-32 (1 pi.). 



t Quart. Journ. Micr. Sci., xlv. (1902) pp. 637-52 (1 pi.). 



t Bull. Soc. Zool. Fiance, xxvii. (1902) pp. 119-23. 



§ Zool. Anzeig., xxv. (1902) pp. 375-9. 



|| Comptes Rendus, cxxxiv. (1902) pp. J 235-8. 



