42 SUMMARY OF CURRENT RESEARCHES RELATING TO 



becomes increasingly apparent that, in many cases, the conception of a 

 species held by the older investigators must be broadened to include a 

 group of closely related forms. One has but to think of such species 

 as Distomum appendiculatum of fishes, and D. cygnoides of amphibians, 

 to understand what confusion is likely to arise from a too rigid anti- 

 pathy to an increase of specific terms. Thus, Distomum variegatum 

 Rud., from the lungs of anurous amphibians, turns out to be another 

 so-called " species " that has to be resolved into a group of " modern 

 species." 



Stafford has studied this form in many hundreds of cases ; he de- 

 scribes their general structure, and he gives good reasons for establishing 

 five new species under the genus Hccmatoloechus proposed by Looss. 



Production of Hydatid Cysts from Scolices.* — Prof. Perroncito has 

 observed that scolices of Tcenia echinococcus may form hyatid cysts. 

 The scolex secretes a cuticular membrane and breaks up completely, as 

 the scattered hooklets show. His observation throws light on the serious 

 consequences which are known to follow the opening of a cyst in the 

 peritoneal cavity ; the liberated heads settle down and form fresh 

 hydatids. 



Life-History of Bothriotaenia proboscidea.f — G-. Schneider has 

 found the young forms of this tapeworm — a common parasite of Baltic 

 salmon — in the stomach and intestine of the herring. But there must 

 be some previous host through which the herring is infected, and there 

 must be some non-marine host by which the perch, trout, and pike of 

 the Genfer-See (quite isolated from the sea) are infected with the said 

 tapeworm, for, as Zschokke has shown, it often occurs in them. 



Incertee Sedis. 



Budding of Rhabdopleura normanni.J — C. Vaney and A. Conte 

 describe the regeneration of individuals and the lateral budding of the 

 stalk in this interesting animal. In no case did their specimens show 

 blastogenic individuals incompletely developed and giving rise to a 

 series of buds on the stalk, as in those studied by Ray Lankester. The 

 authors emphasise the close affinities between Rhabdopleura and endo- 

 proctous Bryozoa. 



Heart of Enteropneusta.§ — "VV. E. Ritter has independently reached 

 conclusions similar to those of C. Dawydoff || in regard to the structure 

 and significance of the heart in Enteropneusta. Dawydoff has stated 

 (1) that the so-called " Herzblase " (Spengel) or " Pericardiablase " arises 

 as a blind vesicle by abstriction from the coelom in the dorsal portion of 

 the proboscis ; (2) that the side of the vesicle- wall turned towards the 

 chorda invaginates into the cavity of the vesicle to form ultimately a 

 blood-sinus, which is the real heart, the outer primary vesicle being the 



* Bull. Soc. Zool. France, xxvii. (1902) pp. 150-1 (1 fig.)- 



t SB. Ges. Naturfreimde Berlin, 1902. pp. 28-30. See Zool. Centralbl., ix. 

 902) pp. 198-9. \ Comptes Rendus, cxxxv. (1902) pp. 748-50. 



§ Zool. Anzeig., xxvi. (1902) pp. 1-5 (3 figs.). 

 || Op. cit, xxv. (1902) p. 551. 



