250 SUMMARY OF CURRENT RESEARCHES RELATING TO 



from tlic hypoblast, and there are not inconsidcrablo resemblances 

 between the rotifer and the larva (trochophorc) of Poli/gorilius. 



With regard to the mode of reprodnction of Botifer vulgaris the 

 author has only been able to confirm anew the well-known fact that this 

 is effected by parthcnogcnetic means. The objects that Zacharias was 

 at one time inclined to look upon as cavities filled with spermatozoa 

 appear to be jiarasitic in origin. The author concludes with expressing 

 the hope that Ganiu will make more generally accessible the results 

 of his observations on CaUidina parasitica ; these, which ai^jiear to 

 indicate the existence of a second mode of formation of ova in the 

 Philodinidfc, have as yet been published in the Russian language only. 



New Floscularia.* — A preliminary descrii)tion, stated to be by 

 Dr. C. T. Hudson, is given of a new Floscularia (F. mutahilis) from 

 localities near Birmingham. It is remarkable for having a disk with 

 only two lobes; for possessing what ajipear to be two eyes on the 

 dorsal lobe, near its summit ; and for its habit of altering the shape 

 of its disk till it somewhat resembles that of an CEcistes or Limnias, 

 and then of swimming by vibrating the short setfe that surnnmd the 

 edge of the disk. It generally swims backwards, circling very slowly, 

 and sure to be soon pulled up by some obstacle. Now and then it has 

 a fit of energetic straight swimming, but even then it is usually stern 

 foremost. 



Coelenterata. 



Origin of Sexual Cells in Obelia.j — C. Hartlaub was led to this 

 investigation chiefly by the work of Weismaun on the origin of the 

 sexual cells in the HydromedusaB. The specimens studied were most 

 satisfactorily killed by hot sublimate or picrosulphuric acid ; 1/2 per 

 cent, osmic acid was found useful, but specimens treated with it must 

 not be afterwards placed in alcohol. 



The female cells were found to have their seat of origin in the 

 ectoderm of the manubrium, and the first ova were constantly formed 

 on the manubrium ; here also the ova must have primitively been 

 matured, and their present position at a varying distance from it is 

 the result of some change that has been effected during their phyletic 

 development ; the young eggs in the ovary always lie in the ectoderm, 

 but a number of them pass into the endoderm for maturation. 



In the early days of free life the males of 0. adelungi and 0. 

 helgolandica — two new species described at the commencement of the 

 paper — exhibit a differentiation of germinal cells at the base of the 

 manubrium, and eventually in the proximal third of the radial canal ; 

 in another species, however, a continuous development of germinal 

 cells was observed outside the spermarium. In the two sjiecies just 

 mentioned there is an ectodermal thickening, which is homologous to 

 that which functions as the ovary in the female ; in fact, it is probable 

 that all the male germ-cells are differentiated in this, and make their 

 way thence to the spot where they are matured. 



The author thinks that he has succeeded in his aim of demon- 



* Midland Natural., viii. (1885) p. 33 (1 pi.). Dr. Hudson writes us that this 

 was extracted from a letter from him and published with(;ut his knowledge. 

 t Zeilschr. f. Wiss. Zool., xli. (1884) pp. 159-85 (2 pis.). 



