ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 255 



all sponges. With regard to the gemmulce. Dr. Goette agrees with 

 Lieberkiihn that these are groups of sponge-cells. At first they are 

 round masses of sub-rotund sponge-cells which then form yolk cen- 

 trally. The peripheral cells, radially disposed, eventually form a 

 continuous epithelium, the cells of which end, internally, with broad 

 truncated bases. The amphidiscs are formed in these bases, not in the 

 convex external portions. A cuticle is developed, but the unorganized 

 mass of gemmula-cells soon creeps from it to form a new sponge. 

 This is really parallel to the manner in which, after disapj)earance of 

 the ectoderm, the larval metamorphosis of Spongilla takes place from 

 an unorganized mass of equivalent entoderm cells. 



Observations on some Fresh-water Sponges.* — F. Vejdovsky 

 describes some specimens of Sjpongilla sibirica from the Danici, which 

 he states agrees essentially with the North American >S'. fragilis 

 Leidy, whilst it differs from it in some details. The polar air-tube of 

 S. fragilis plays an important part in the existence of the gemmules. 

 It is in direct connection with the low superior process of the gem- 

 mule, which is generally regarded as an aperture of issue for the 

 young sponge ; but whether it is really an aperture cannot be stated 

 with certainty. It rather appears much more probable that the polar 

 process is completely closed by the horny membrane by which the 

 space within the gemmule appears to be completely cut off from the 

 air-tube. The air-tubes of the dry gemmules are occupied by large 

 air-bladders. They are of comparatively more considerable dimen- 

 sions than in any other species, and must contain a larger quantity of 

 air in order to sustain the certainly heavier groups of gemmules for a 

 time at the surface of the water. 



Spongilla fragilis, and a New Species of Spongilla.t — H. J. 



Carter alludes to the discovery of Spongilla fragilis in the Wye, and 

 describes a new species (S. MacJcayi) from Nova Scotia. 



The most remarkable point presented by the latter is that its 

 flesh-spicule is identical with that of Meyenia Everetti, whose stato- 

 blast is covered with a thick crust of long and large birotules, denticu- 

 lated with recurved teeth like those of Myenia Baileyi, &c., showing 

 that this kind of flesh-spicule may be present in totally different 

 species of fresh-water sponges, unless it should be owing to the 

 presence and proximity of M. Everetti, which grows in the same lake. 

 The spiculation, too, both skeletal and flesh, is almost identical with 

 fresh-water sponge-spicules from alluvial deposits in Bavaria. 



Protozoa. 



Erythropsis agilis.| — E. Hertwig brings forward a number of 



facts to show that his lately discovered E. agilis cannot, as Vogt 



thinks, be Spastostyla sertulariarum.§ It is nearly three times the 



size ; its tail-like muscular appendage is 3-4 times the length of the 



* SB. K. Bohm. Gesell. Wiss., 1884, pp. 55-60 (1 pL). Ann. and Mag. Nat. 

 Hist., Ixxxv. (1885) pp. 13-18. 



t Ann. and Mag. Nat. Hist., Ixxxv. (1885) pp, 18-20. 

 t Zool. Anzeig., viii. (1885) pp. 108-12. 

 § See this Journal, ante, p. 77. 



