ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 557 



insufficiently known, gives a precise detailed description of this species, 

 which is also the sole representative of a distinct family. The previous 

 literature of Isis is reviewed, and a note of its distribution as far as 

 recorded is given. 



Porifera. 



New Clionid.* — E. Topsent describes Cliothosa seurati g. et sp. n., 

 a new boring sponge, from the Gambier Islands. There are no somatic 

 microscleres, and the choanosomic asters are amphiasters. 



Protozoa. 



* Biometrical Study of Conjugation in Paramcecium.t — R. Pearl 

 has made a study of variation and correlation in conjugating and non- 

 conjugating examples of Paramecium cat/datum. The author's aim has 

 been to determine whether the portion of the Paramecium population, 

 which is in a state of conjugation at a given time, is differentiated in 

 respect of type or variability, or both, from the non-conjugating portion 

 of the population living in the same culture at the same time ; and 

 further whether there is any tendency for like to pair with like 

 (" homogamy "), and if so, how strong this tendency is. The results 

 showed that there is a differentiated "conjugant type " of Paramecium ; 

 and that this " conjugant type " is relatively fixed and constant under 

 varying environmental conditions, as compared with the general popula- 

 tion in fission generations. Thus it follows that if the individual 

 Paramacia of a given race must conform to a definite and relatively 

 fixed morphological type every time they conjugate, what they may 

 acquire during fission generations is clearly of no particular account to 

 the evolutionary history of the race in the long run. 



Rhizopoda in Human Spinal Fluid.}— V. Ellermann describes from 

 the spinal fluid in two cases of poliomyelitis acuta, rhizopods showing 

 a well marked development of filose pseudopodia. They bore no 

 resemblance to polynuclear leucocytes, but were quite characteristic. 

 No bacteria were found associated with them. 



Trypanosome of Horse.§ — J. J. Vassal describes a trypanosome 

 affecting horses in Annam. Laveran and Mesnil|| have conducted a 

 series of immunity experiments with a view to determining its relation 

 to the organism of Surra, which it resembles. Their main conclusion is 

 that it is probably a variety of the same ; it is not distinct from Surra 

 in the sense that Nagana is. 



Spirillum of Bat.f — C. Nicolle and C. Comte describe a fatal 

 spirillum disease of Vespertilio Jcuhli from Tunis. The source of infec- 

 tion is apparently undetermined. 



* Bull. Mus. Nat. Hist., 1905, pp. 94-6. 



+ Proc. Roy. Soc, Series B, lxxvii., No. B 518, pp. 377-83. 



% Centralbl. Bakt. Parasit., xl. (1906) heft 5, pp. 648-53 (1 pi. and 1 fig.). 



§ Ann. Inst. Pasteur, xx. (1906) pp. 256-95. 



|| Tom. cit., pp. 296-303. ^ Tom. cit., pp. 311-20 (1 pi.). 



