424 SUMMARY OF CURRENT RESEARCHES RELATING TO 



wall of the vessel which faces the ectoderm, and surround the lumen in 

 sickle-like fashion. The "genital sinus" is merely a cleft, formed by 

 the elevation of the fine epithelium, and has no important morpho- 

 logical significance. In PL pileus the primordia of the reproductive 

 organs occur not only in the eight meridional vessels, but also in the 

 tentacular and stomachic vessels. 



Halcampella in the Black Sea.* — Th. A. Wryagevitch has found, 

 on the surface of mussel shells in the Bay of Balaclava, a minute 

 Actinarian which is a (possibly new) species of Halcampella. The 

 Actinarian is placed within a membranous investment, which attaches 

 it to the surface of the mussel. This is the first record of a Halcam- 

 pella in the Black Sea. Further details are promised. 



North American Hydromedusae.| — Charles W. Hargitt has com- 

 pleted two parts of a synopsis of North American Hydromedusas. It 

 gives a key to the families, genera, and species of Tubularige and 

 Campanularise. 



Porifera. 



Studies on the Hexactinellida.J — Prof. Isao Ijima has published 

 an instalment of the results of seven years' study of the Hexactinellida. 

 It deals with the Euplectellidae — and describes in detail Euplectella 

 imperialis Ij., E. marshalli Ij., E. oweni Herkl. and Marsh, E. curvistel- 

 lata sj>. n., Eegadrella okinoseana Ij., B. homeyamai Ij., B. phoenix 

 0. Schm., and Walteria leuckarti Ij. The illustrations are superb. 



Protozoa. 



Protozoa and Bacteria.§ — S. Prowazek, among other observations, 

 records a fatal infection with bacteria in Vorticella microstoma. The 

 specimens appeared in a culture, and showed within their macronuclei 

 numerous bacteria, which produced liquefaction of the nuclear sub- 

 stance. As this progressed, various pathological symptoms appeared, 

 including a vacuolation of the protoplasm. An interesting point was 

 the fact that, as the disease progressed, the normal digestive proceses 

 became entirely suspended, so that bacteria within the food-vacuoles 

 not only remained undigested, but actually multiplied and swam freely 

 in the fluid contents of the vacuole. At this stage the irritability of 

 the stalk seemed unimpaired, which suggests that the nucleus has more 

 to do with nutrition than with the muscular contractions. 



Systematic Work on Plagellata.||— Dr. G. Senn gives an account 

 of the structure and functions, distribution and systematic relationships 

 of the Flagellata. The characters of chief systematic importance are 

 the following : — (a) The anterior apex and the insertion of the flagellum 

 and the mode of nutrition ; (b) the form of the contractile vacuoles and 

 the nuclear structure ; (V) the general organisation of the plasma. Seven 



* Zoo]. Anzeig., xxiv. (1901) pp. 246-50 (!) figs.). 

 t Amer. Nat., xxxv. (1901) pp. 301-15, 379-95 (32 figs.). 

 t Journ. Coll. Sci. Univ. Tokyo, xv. (1901) pp. 1-299 (14 pis.). 

 § Zool. Anzeig., xxiv. (1901) pp. 250-2 (2 figs.). 



il Engler and Prantl, • Die natiirl. Pflanzenfam.,' Lief. 202-3, i. Teil, Abteilun°- a, 

 Bogen 7-13, Leipzig, 1900, 4to. See La Nuova Notarisia, xii. (1901) pp. 38-40.° 



