ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 61 



Factors at work in the imitations are essentially different from those 

 ■acting in the Amoebai. In particular, almost all the imitations based 

 on local changes in surface-tension break down completely. The surface- 

 tension theory is shorn of the trophies of its prowess — its supposed full 

 explanation of most of the activities of Amcebas — and bears instead the 

 record of a complete defeat. 



British Fresh-water Rhizopods.* — J. Cash describes a number of 

 new and little-known forms, from Cheshire and Epping Forest. Testa- 

 ceous forms occur in considerable abundance in wet Sphagnum, and 

 amongst the rootlets of such mosses as Philanotis fontanel and Anla- 

 co milium palustre. Thelgenera represented are Difflugia, Nebela, Hyalo- 

 sphenia, Quadrula ; the Euglyphina occur also in great variety. A 

 remarkable naked reticulate Rhizopod, Penardia g. n., is described. 



Asymmetry and Spiral Swimming.f — H. S. Jennings discusses the 

 unsymmetrical or spiral type of structure seen in Infusorians and in the 

 Rattulidas among Rotifers. It is characteristic of animals which swim 

 in spirals, and is to be considered as an adaptation to the spiral course. 

 The spiral course is the simplest device for permitting an organism to 

 make progress in a given direction through the free water, without having 

 the parts of the body elaborately adjusted so as to balance each other 

 accurately. Not having such elaborate adjustment, small organisms 

 would swim in circles, were it not for their revolution on the long axis 

 •of the body. This converts the circle into a spiral course, permitting 

 progress to be made. In such spiral course the organism maintains its 

 body in a definite relation to the axis of the spiral, the same surface 

 always facing outward, the opposite surface facing the axis of the spiral. 

 Many organisms which swim in this manner have the body structurally 

 adapted to this movement, the form approximating in some degree to a 

 segment of a spiral. In these unsymmetrical organisms moving in 

 spirals, the method of reaction to most stimuli is closely correlated with 

 the unsymmetrical form. 



New Opalinid.J — C. A. Kofoid describes the structure of Protophyra 

 ovicola g. et sp. n., a newciliate Infusorian, obviously an Opalinid, from 

 the broad sac of Littorina rudis. Its single contractile vacuole, posterior 

 to a spherical macronucleus, and the absence of special structures such 

 as the hooks of internal rods of Hoplitophrya, stamp this new genus as 

 one of the least specialised members of the Opalinidas. There is a micro- 

 nucleus, which is known to occur in but a single other species of the 

 family, viz. Anolophrya branrhiarum. The specialisation of the new 

 genus lies in its fine ciliation, the marginal zone of cilia, and the adaptive 

 form of the animal. 



Trypanosomes in Anglo-Egyptian Soudan.§ — A. Balfour gives some 

 notes regarding the occurrence of trypanosomes in the blood of a donkey. 



* Journ. Linn. Soc, (Zool.) xxix. (1904) pp. 218-25 (1 pi.). 



t Mark Anniv. Vol., 1903, pp. 315-37 (10 tigs.). 



t Tom. cit., pp. 111-120 (1 pi.). 



§ Brit. Med. Journ., 1904. pp. 1455-6. 



