ZOOLOGY AND ROTANY, MICROSCOPY, ETC. 671 



glands, the ciliated rings, the ectoderm of the intertrochal zone, nervous 

 system, gut, mesodermal structures including coelome, and nephridia. 

 There are comparative notes on other Echiuridge. Echiurus and Thalas- 

 sema are closely related by several important characters : they are distinct 

 from the Annelids. If placed amongst Annelids they must stand in an 

 isolated group. 



Cirrus and Elytron in Aphroditidae.*— H. Duncker has set him- 

 self the problem of settling the question of homology between these two 

 structures in this family, and fills 140 pages with the record of his 

 investigations. On histological and topographical grounds he concludes 

 they are homologous. Normally they always exclude each other, and 

 are the only innervated organs of the parapodium. 



New Species of Oligochaets.t— L. Cognetti de Martiis describes 

 the following new forms — Pheretima habereri, Ph. marenzelleri, Ph. 

 ambigna, Tritogenio morosa. 



Neniatohelminthes. 



Conditions of Development in Ascaris vitulorum.}: — L. Jammes 

 and A. Martin find that the receptivity of the host depends in the first 

 place on its temperature. The nature of the digestive fluids is also 

 important ; the succession of an acid and an alkaline medium is favour- 

 able to development. Susceptibility to parasitism varies with age and 

 physiological condition. It is suggested that the development of the 

 parasites is in some measure conditioned by pre-existing abnormal con- 

 ditions in the host. 



Maturation in Ascaris canis.§ — H. Marcus has studied the egg 

 and sperm maturation in this species of Ascaris. The following are the 

 more important of his results. He finds that conjugation of the 

 chromosomes takes place. Both maturation divisions are longitudinal, 

 consequently one must be a genuine reduction division. The chromo- 

 somes show a " Duplicitat." In the original sex-cells, a reduction of 

 the number appears again to occur through " Konjunktion " of the 

 chromosomes ; a symmixis is therefore probable. On the ground of 

 far-reaching " Oonomery " inside the chromosomes both maturation 

 divisions can be regarded as reduction divisions. The centrosome arises 

 in the nucleus ; probably the centrosome of the spermatid persists and 

 enters the egg in the nucleus of the spermatozoon. 



Oxyuris in Vermiform Appendix. || — H. Schoppler describes a case 

 in which a string of eggs of Oxyuris vermicularis occurred in the vermi- 

 form appendix of a child. The eggs were arranged exactly as they lie 

 within the parent worm, and had undergone partial development. It is 

 suggested that the worm, having migrated to the appendix, underwent 

 maceration, but that the eggs, on account of their more resistant cover- 

 ings, had withstood this process. 



* Zeitschr. Wiss. Zool., lxxxi. (1906) pp. 191-342 (1 pi. and 33 figs.). 



t Atti R. Accad. Sci. Torino, xli. (1906) pp. 777-90 (1 pi.). 



% Comptes Rendus, cxliii. (1906) pp. 189-90. 



§ Arch. Mikr. Anat , lxviii. (1906) pp. 441 90 (2 pis. and 10 figs.). 



| Centralbl. Bakt. Parasitenk., xli. (1906) pp. 453-5 (1 fig.). 



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