ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 183 



are more common over deeper water. When kept in a bright light they 

 become almost pure white, whatever the original colour may have been. 



Porifera. 



Structure of the Styles of Tethya.*— G. C. J. Vosmaer and 

 H. P. Wijsmann have made a study of the structure of the silicious 

 styles of Tethya lyncurium. The concentric layering of the silicious 

 substance is said not to' be due to the alternation of thick silicious layers 

 and thin organic layers. The whole style consists of an organic axial 

 thread of " spiculin," an external spicule-sheath (in Kolliker's sense), 

 and between these the amorphous layered hydrate of silica (" spicopal"). 



Genus Receptaculites.f — F. Chapman gives some notes on repre- 

 sentatives of this genus from Victoria, and on R. australis from 

 Queensland. In Australia the genus ranges from the Silurian to the 

 Carboniferous. 



Protozoa. 



Cilia and Trichocysts.J — A. Schuberg has made a detailed study of 

 the minute structure of the cilia and trichocysts in Stentor cvcruleus, 

 Paramecium caudatum, Frontonia leucas, and other forms. He demon- 

 strates a fine " terminal portion " of the more substantial basal portion, 

 and the spiral twisting of the cilium. There is a differentiation into an 

 axial portion and a sheath. There are basal corpuscles at the roots of 

 the cilia. In the trichocysts also there are intricacies : thus the author 

 distinguishes the " head " and the " hair-like process." 



Pseudospora volvocis.§ — Muriel Robertson describes what seems to 

 be Pseudospora volvocis Cienkowski, which Butschli places among the 

 Isomastigoda. It has three adult forms, amoeboid, flagellate, and radial 

 (the last a direct reaction to external conditions). There is a single 

 nucleus with a membrane ; it divides by mitosis. In gametogenesis the 

 nucleus becomes converted into a sphere, the nuclear substance of which 

 appears to be derived from the rays of the original cell nucleus. The 

 karyosome is extruded from the sphere. The sphere segments, to form 

 a large number of gametes. The gametes conjugate in pairs, forming 

 zygotes, which develop into the adult form. 



Trypanosoma of Rat.|| — K. Byloff has studied the behaviour of 

 T. leivisi when inoculated into wild and tame rats. The adults, injected 

 into peritoneal cavity, pass slowly into the blood, and from the second to 

 the fourth day division and young forms appear there. Divisions 

 clearly take place into the peritoneal cavity, the products passing into 

 the blood via the lymph and possibly also by direct passage into the 

 vessels. Growth and continued divisions of these forms take place 

 rapidly, resulting in very small elements which are present in con- 



* Proc. k. Akad. wiss. Amsterdam (1905) pp. 15-28. 

 t Proc. Roy. Soc. Victoria, xviii., n.s. (1905) pp. 5-15 (3 pis.), 

 j Arch. Prot., vi.. (1905) pp. 61-110 (2 pis.). See also Zool. Zentralbl., xii. (1905> 

 pp. 799-803. § Quart. Journ. Micr. Sci., xlix. (1905) pp. 213-30 (1 pi.). 



U SB. Akad. Wiss. Wien, cxiii. (1904) pp. 111-38 (2 pis.). 



