444 SUMMARY OF CURRENT RESEARCHES RELATING TO 



cleavages and nuclear divisions without cytoplasmic divisions were 

 observed, and ciliated bodies unlike normal embryos were often formed. 



Nematokelmintb.es. 



Rachis in Ovaries and Testes of Nematodes.* — Alfred Mayer 

 extends the recent observations of Marcus, and finds that there are 

 numerous nuclei in the rachis of the gonads of both sexes in Ascaris 

 megalocephala and A. lumbricoides. He compares the rachis with the 

 nucleated cytophore in the spermatogenesis of various invertebrates, such 

 as Glitellio. 



Anguillula intestinalis.f — Stursberg discusses the case of a 

 German field labourer whose faeces showed the Rhabditis embryos of 

 this Nematode. He had repeatedly drunk water from the cooling- 

 canals of a manufactory in which foreigners were at work. 



Ascaris halicoris.J — Von Linstow describes Ascaris halicoris Baird 

 from the pylorus of the dugong. 



Cetacean Echinorhynchi.§ — A. Porta gives a full account of the 

 structure of Echinorhynchus capitatus von Linstow, from Psendarca 

 crassidens Gray and Globicephalus svineval Flower. Four other species 

 from Cetaceans — E. porrigens Rud., E. pellucidus Leuck., E. turbinella 

 Dies., and E. brevicollis Malm. — are compared with E. capitatus, and the 

 author proposes to include the five in a new genus, Bulborhynchus. 



Embryology of Strongylus filaria.|| — C. Struckmann gives an 

 account of the oogenesis, spermatogenesis and fertilisation in this 

 Nematode. In both oogonia and spermatogonia there are twelve chromo- 

 somes which form tetrads, equivalent to bivalent chromosomes. There 

 are two large, two medium, and two small tetrads. The phases of 

 ovum and sperm maturation agree in the behaviour of the chromatin 

 as regards reduction. The tetrad forms of the first reduction spindle 

 are characteristic and are comparable to the chromatic elements of 

 Ascaris. In fertilisation the sperm does not after entering the egg 

 penetrate far, but remains near the periphery, and here the male pro- 

 nucleus is developed. The pronuclei arise mostly at opposite poles, and 

 only approach the centre of the egg for the formation of the first 

 segmentation spindle. 



Platyhelminthes . 



Sexual Organs and Development of a Tapeworm.^ — T. B. Rosseter 

 gives some details regarding the generative organs in Drepanidotcenia 

 undulata (Krabbe). This tapeworm, which occurs in a number of avian 

 hosts, in the present instance was found in Turdas musicus. The develop- 

 ment of the 6-hooked embryo was followed within the uterus, where it 



* Zool. Anzeig., xxx. (1906) pp. 289-97 (6 figs.), 

 t SB. Niederrbein. Ges. Nat. Bonn, 1905, Section B, pp. 28-9. 

 j Journ. and Proc. Asiatic Soc. Bengal, i. No. 10 (1905) pp. 258-60 (1 pi.). 

 § Zool. Anzeig., xxx. (1906) pp. 235-71 (63 figs.). 



|| Zool. Jahrb. Abt. Anat., xxii. (1905) pp. 577-628 (3 pis. and 18 figs.). 

 i Journ. Quekett Micr. Club, 1906, pp. 269-74 (1 pi.). 



