532 SUMMARY OF CURRENT RESEARCHES RELATING TO 



somes of sister-cells may be quite different. Those of the one cell 

 retain the original character, they remain " primitive chromosomes " ; 

 those of the other suffer diminution, and in Ascaris megalocephala the 

 remnant of each primitive chromosome breaks up into a number of 

 small " somatic chromosomes." The question arises, is this differentia- 

 tion of chromosomes autonomic ? that is, does each chromosome in 

 certain cell-divisions divide into two different halves ; or, does it depend 

 on differences in the surrounding cytoplasm — on protoplasmic dif- 

 ferentiations which determine whether the chromosomes are to persist 

 along a definite cell-lineage as primitive chromosomes, while in other 

 lateral lineages, diminution sets in ? After a discussion of the problem, 

 Boveri concludes that the protoplasmic differentiation determines the 

 persistence or reduction of the chromosomes. 



Platyhelttiinth.es. 



Terrestrial Planarians from North-East Africa.* — Camillo Moll 

 describes a collection made by Oscar Neumann in north-east Africa. 

 It includes Amblgplana nigrescens sp. n., A. aberrana sp. n., A. neu- 

 manni sp. n., and Platydemus montanus sp. n., — within the family 

 Blvynchodemidse. We record the names, since relatively few terrestrial 

 Planarians have hitherto been recorded from the African continent. 



Sense-Organs in Digenetic Trematodes.f — D. Ssinitzin finds on 

 definite points of the body-surface, within the cuticula, clear vesicles 

 containing transparent substance, in which a rod-like structure and some 

 granules can be recognised. A nerve-fibre penetrates into the vesicle. 

 The cuticula over the slightly protruding vesicle is relatively delicate, 

 and may bear fine hair-like processes. 



Ssinitzin distinguishes : (1) sensory vesicles, without hairs ; (2) 

 sensory vesicles, with short immobile hairs (0 * 0006 mm.) ; (3) sensory 

 vesicles, with long (0 ' 01 mm.) immobile hairs ; (4) sensory vesicles, 

 with mobile hairs of moderate length ; and (5) sensory vesicles, with 

 long flagella-like mobile hairs. 



Sexually mature Trematodes exhibit only the first two kinds of 

 sensory organ ; redire show the first three kinds ; in cercarias all forms 

 occur. The research refers to Trematodes found in fresh-water molluscs, 

 such as Amphistomum subdavatum and Distomum folium. 



Echinostomum garzettse.f — W. Gr. MacCallum describes this new 

 species collected by W. Volz while in Benakat (Lematangilir) from the 

 intestine of Garzetta nigripes Temm. All the other described forms 

 of Echinostomum from birds differ very decidedly from Echinostomum 

 garzetta, though this new form falls readily into the smaller group of 

 those closely related to E. echinatus. 



Three Species of Paramphistomum from Mammals.§ — F. Fis- 

 choeder describes Paramphistomum explanatum Crepl., from Buffelus 



* Zool. Jahrb., xx. (1904) pp. 471-90 (1 pi.), 

 t Zool. Anzeig., xxvii. (1904) pp. 767-70 (5 figs.). 

 % Zool. Jahrb., xx. (1904) pp. 541-8 (1 fig.). 

 § Tom. cit., pp. 453-70 (2 pis. and 3 figs.). 



