50 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Chromatin-Reduction in Somatic Cells.* — Kristinc Bonnevie finds 

 that this interesting process occurs (as O. Meyer described) in Ascaris 

 lumbricoides ; but no hint of it was seen in Strongylus paradoxus or 

 Bhabdonema nigrovenosa. The process was seen in four generations of 

 cells ; each chromosome breaks up in the prophasis into three spherules, 

 of which the two lateral ones are thrown off. The remaining middle 

 piece does not break up into small particles, as in A. megalocepliala. It 

 is also noted that the position of the second polar body is quite irregular, 

 and that it is sooner or later absorbed by the cell to which it is apposed. 



Strongyloides intestinalis. j — Dr. E. P. Strong records a fatal case of 

 infection with this Nematode in Baltimore, U.S.A., in a man of German 

 birth, and four other cases (one fatal) in Manila. In no case did he find 

 embryos in the blood, nor eggs nor adults in the faeces, though embryos 

 of the rhabditis type occurred there abundantly. These embryos gave 

 rise to free-living males and females producing filariform larvae, but in 

 some cases this generation was omitted, and the rhabditiform embryos 

 gave rise directly to filariform larvae. The adult females of the strongy- 

 loid type were found abundantly in the duodenum and jejunum of the 

 host. No males of this generation were found. No suggestions are 

 made as to the means of infection. 



Heterodera schachtii.ij: — Willot found that in 1901 the brown female 

 nematodes in the beetroot, which are usually dead and empty in July and 

 August, were full of living eggs, embryos, and larvae even in September. 

 He sees in this confirmation of what he indicated in 1890, that warmth 

 and moisture cause the dead females to swell and rupture, allowing the 

 larvae to escape. The prolonged drought of last summer hindered this 

 mechanical rupture of the vaginal canal. 



Platyhelininth.es. 



vian Cestodes.§ — 0. Fuhrmann discusses the structure and relations 

 of several new Cestodes which have been recently described by various 

 authors. He especially criticises descriptions by Sintzin || of various new 

 forms, rejecting entirely two new genera (Trichocephaloides and Copesoma) 

 founded by this author for tape-worms which in the one case at least are 

 not even new species. 



Germinal Layers in Cestoda.1T — G-. Saint-Berny discusses the diffi- 

 culty of bringing the early stages in the development of Cestodes into 

 line with those of other Metazoa. If one insists on finding the two 

 primary germinal layers in Cestodes, the olements of the external 

 envelope, the " vitellophagous cells," have most claim to be regarded 

 as endoderm. But this is far-fetched, and the author prefers to say 

 that the abbreviated development of these parasites has resulted J in 



* Jenaische Zeitschr. Naturwiss., xxxvi. (1901) pp. 275-S8 (2 pis.). See Zool. 

 Centralbl., viii. (1901) p. 640. 



t Jotms Hopkins Hosp. Rep., Baltimore, 1901, pp. 91-132 (2 pis.). 



% Comptes Rendus, exxxiii. (1901) p. 703. 



§ Centralbl. Bakt, xxix. (1901) pp. 757-63. 



|l Arb. Zool. Lab. Univ. Warschau, 1896 (Russian). 



Tf Arch. Parasitol., iv. (1901) pp. 333-52. See Zool. Centralbl., viii. (1901) 

 pp. 748-9. 



