ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 133 



The evidence seems to indicate that the Paramecium is divided by the 

 approach of the two pseudopods. On the basis of the surface-tension 

 theory the surface-tension of the Amoeba would require to be much 

 higher than 388, and probably higher than 1118 dynes per centimetre. 

 But the surface-tension of protoplasm is only about 50 dynes per centi- 

 metre, and it is probably at best an insignificant factor in the process of 

 feeding in Amoeba. 



'^ 



Ciliary Current in Free-swimming Faramoecium.* — S. 0. Mast 

 and K. S. Lashley note that when these Infusorians are at rest and are 

 feeding, a cone-shaped current from a considerable distance in front of 

 the animals proceeds down the oral groove towards the mouth, Ijut 

 that in the case of free-swimming individuals there are no appreciable 

 movements of particles either in front of or along the sides of the 

 animals. In free-swimming Parama^ckun, Stmtor^ and Spirostomum, 

 there is no continuous feeding-cone, as there seems to be in Rotifers. 

 Water is sucked towards the free-swimming Infusorians through only a 

 very short distance, probably a distance not over twice the length of the 

 cilia. This distance is not great enough to make any warning of un- 

 favourable environment ahead, which may be due to such currents, of 

 any appreciable value. 



The feeding-cone is produced by these organisms : (1) when they 

 are at rest and are feeding ; (2) during locomotion, if they are retarded 

 l)y lateral contact with resistant substances which are not uniformly 

 distributed (e.g. bacterial masses, the substratum, etc.), or if the rate of 

 locomotion is increasing or if it is decreasing (provided the decrease in 

 rate is due to a reversal or a decrease in the activity of the cilia on the 

 body without a similar change in the activity of those in the oral groove) ; 

 and (3) in the avoiding reaction, but not until after the stimulus which 

 causes such reactions has been received and the animals begin to turn. 

 It is not the cause of the avoiding reaction. 



Trypanophis grobbeni.t — J. F. M. Floyd gives an account of this 

 Flagellate Infusorian, which, as Keysselitz records, is abundant through- 

 out the gastro-vascular system of the Siphonophore, Halisfemma 

 tergcstinum, where it can be detected even with a dissecting lens. Xone 

 of the author's preparations showed a karyosome within the nucleus 

 (" trophonucleus ") nor a kinetonucleus at the base of the flagella. The 

 free flagellum springs from a more or less distinct basal granule. The 

 attached fiagelkim originates from the edge of the body at a point either 

 on a level with the basal granule of the' free flagellum or a little in 

 advance of it. Along the whole length of the animal is a row of 

 " chromatic bodies." 



New Species of Opercularia.i — X. M. Grier describes Opercularia 

 waUffreni sp. n., found growing profusely on Sagittaria, in colonies of 

 2-200 zooids, which assume a nodding or pendant position after con- 



* Journ. Exper. Zool., xxi. (1916) pp. 281-93 (6 figs.). 



t Proc. Roy. Phys. Soc, xx. (1910) pp. 62-4 (1 pi.). 



X Trans. Amer. Micr. Soc, xxxv. (1916) pp. 138-9 (1 pi.). 



