354 SUMMARY OF CURRENT RESEARCHES RELATING TO 



that inhabit stagnant water where conditions are most variable and 

 where only plastic forms could live permanently by adjusting themselves 

 to their varying conditions of life. 



Copepod Parasites of Tunicates.* — E. Chatton discusses the Cope- 

 pod genus Ophioseides, the terminus of degeneration in the series of 

 Ascidicolidaj, and describes 0. joubini sp. n. from Microcosmus sabattieri. 

 The female has a vermiform, sub-cylindrical body, the male is 

 harpacticiform. 



Armulata. 



Multiple Cephalisation in Syllis.f —A. Michel describes several 

 cases, the most striking being in a specimen of Syllis arnica, where he 

 found twelve supplementary heads on successive rings and appendages as 

 well as eyes. In fact some of the abnormal rings were complete heads 

 of the stolonial type. 



Innervation of the Pharynx in Oligochaeta.l — Vaclav Maule gives 

 a detailed account of this, with special reference to Pachydrilus (Mesen- 

 chytrseus) beumeri. There are two pairs of pharyngeal ganglia with 

 complex connections. 



Nematohelminthes. 



Development of Nematodes.§— E. Martini finds that bothcoeloblastula 

 and placula embryos are formed, and that both epibolic and invaginate 

 gastrulation occurs. The blastopore and the archenteron entirely 

 disappear. There is no ccelom or mesoblast, but only a mesenchyme. 

 The ectodermic epidermis is represented by the subcuticula and 

 lateral areas. The fore-gut is ectodermic, the mid-gut is formed 

 from two rows of endoderm cells which form a cavity between them, 

 the hind-gut is probably due to ectoderm and mesoderm. It is note- 

 worthy that the sex-cells are easily distinguishable from the somatic 

 cells. 



The development is absolutely determinate from start to finish, that 

 is to say, specific blastomeres form specific organs. There is very little 

 difference in the early ontogeny of different species. The Meromyaria 

 are the most primitive. 



Oxyuris in connection with Appendicitis. || — Fr. Unterberger finds 

 that Oxyuris vermicularis is able to penetrate into the normal intestinal 

 mucosa, but that the membrane shows no appreciable reaction to the 

 parasite. Whether the worm can perforate the wall, and why the deposi- 

 tion of ova sometimes happens in the wall of the intestine, are points that 

 recjuire further investigation. 



* Bull. Soc. Zool. France, xxxiv. (1909) pp. 11-19 (8 figs.). 



t Comptes Rendus, cxlviii. (1909) pp. 438-9. 



\ SB. k. Bohm. Ges. Wiss., 1908, No. ix., pp. 1-21 (2 pis.). 



§ Zeitschr. wiss. Zool., xci. (1908) pp. 191-235 (13 figs.). 



|| Centralbl. Parasitenk., xlvii. (1908) Abth. i., pp. 495-503 (1 fig.). 



