ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 311 



Myxosporidia at Roscoff.* — Jivoin Georgevitch reports on a number 

 of Myxosporidia which he collected from fishes at Roscoff. Out of 

 287 fishes examined 171 had Myxosporidia. Most of these were 

 species of Myxidium which occurred in the gall-bladder, and species of 

 Sphaeromyxa and ChJoromyxum. The infection is usually simple, in 

 fact only one instance, in Syngtiathas acus, was found of a double 

 infection. All the species sporulate in the interior of plasmodia, which 

 are sometimes so large that they completely fill the gall-bladder. The 

 spores are set free by the liquefaction of the Plasmodium ; sometimes 

 the interior of the Plasmodium becomes fluid before the sporulation is 

 completed. In Sphaeromyxa haJbianii in Motella tricirrata the division 

 of a Plasmodium into two was observed. A description is given of 

 Myxidium gadi sp. n., Sphceromyxa yasterostei sp. n., and three other 

 species. 



Orientation of Gonium.t — A. R. Moore calls attention to Mast's 

 investigation | of the orientation of this Flagellate. Mast accounts for 

 the orientation to a directive stimulus (light), by supposing the zooids 

 farthest from the source of light to increase their activity, and thus 

 bring the plane of the colony perpendicular to the lines of the stimulating 

 force. He assumes equal activity of the two flagella in each cell of 

 the colony, the behaviour of the cells varying only in the intensity of 

 their activity. He does not consider the possibility which Moore and 

 Ooodspeed previously § pointed out, viz. that the turning may be 

 accomplished by an inequality in the beating of the two flagella of each 

 oell. This mode of orientation has been observed by Bancroft in Volvox, 

 by Ludloff in Parammcium. There may be a cessation of beat or a 

 reversal of stroke of the flagellum on the stimulated cell. It may be 

 that there is also, as Mast concludes, an increased activity of the cells 

 away from the side stimulated. 



« Bull. Soc. Zool. France, xli. (1917) pp. 86-95 (23 figs.). 



t Journ. Exper. Zool., xxi. (1916) pp. 431-2 (2 figs.). 



X Journ. Exper. Zool., xx. (1916) p. 1. 



§ Univ. California Publications, Physiology, iv. (1911) p. 17. 



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