680 SUMMARY OF CURRENT RESEARCHES RELATING TO 



which gives a systematic account of the known fresh- water Rhizopods of 

 Britain. In the order Amoebina he deals with three families and fourteen 

 genera : — (1) Lobosa (Amoeba, Dactylosphmrium,Mastigama}ba, Pelomyxa, 

 Lithamwba, Ouramccba) ; (2) Reticulosa (Gymnophrys, Biomyxa, Pen- 

 ardia, Chlamydomyxa) ; (3) Vampyrellida (Vampyrella, Hyalodiscus, 

 Nuclearia, Archerina). For the shelled fresh-water Rhizopods the term 

 Conchulina is suggested to replace Testacea, and in this volume the 

 genera Arcella, Pseudochlamys, and Centropyxis are dealt with. It is 

 to be hoped that this publication will stimulate a much neglected study. 



Antarctic Protozoa.* — Olaw Schroder makes a preliminary report 

 on a remarkable type (Cytocladus g. n.) collected by the German South 

 Polar Expedition. They look like large spherical Radiolarians with 

 twelve radial beautifully branched spines. The cytoplasm consists of 

 five much-branched arms arising from a median portion, which lies 

 eccentrically in the skeletal sphere and is not perforated or touched by 

 the spines. A somewhat flat round disk is probably the nucleus, but no 

 central capsule could be definitely distinguished. 



New Species of Cytocladus.f — Olaw Schroder has previously de- 

 scribed two species of this interesting Radiolarian-like genus, and he 

 now describes a third (Cytocladus splnosus sp. n.) from Japan, which 

 is interesting in showing a central capsule divided into twelve branches, 

 surrounded by a very delicate membrane, but showing neither pores nor 

 larger openings. The discovery of the central capsule removes doubt as 

 to the Radiolarian character of this remarkable type. 



Acanthocystis pertyana.J — J. E. Lord describes this Heliozoon, 

 which he found in a pond near Manchester. He points out that it, as 

 defined by Archer, is almost certainly the same as an unnamed species 

 described by Leidy, and is very probably identical also with Perty's 

 A. brevicirrhis. He has been able to prove the presence of a skeletal 

 test in addition to the spines, and notes that this ought to be included 

 in the generic characters. The test seems to consist of short interlacing 

 rods, soldered together by some cementing material. 



Function of Contractile Vacuole. § — Albert Degen has studied the 

 contractile vacuole of Glaucoma colpidium. It is originally an osmotic 

 system, preventing undue imbibition of water, but it aids in respiration, 

 excretion, and perhaps circulation. There is a special vacuole-niembrane, 

 which mediates between the osmotic conditions in the cytoplasm and in 

 the vacuole. The physiological conditions of the diastole and systole 

 are discussed in detail. The factors altering the rate of pulsation are 

 analysed ; thus a rise of temperature above 34° C. accelerates, increased 

 oxygenation of the water accelerates, neutral substances such as cane- 

 sugar and glycerin retard. But this is only an indication of the 

 general scope of Degen's investigation. 



* Zool. Anzeig., xxx. (1906) pp. 448-54 (9 figs.). 



t Tom. cit., pp. 587-90 (1 fig.). 



X Report and Trans. Manchester Micr. Soc. for 1905 (1906) pp. 41-4 (1 pi.). 



§ Bot. Zeitung, lxiii. (1905) pp. 160-202 (9 figs.). 



