ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 157 



be correlated with the turning of the earth on its axis, with the resultant 

 apparent motion of the sun from east to west. Negatively phototaetic 

 micro-organisms of the Northern Hemisphere rotate as a rule in counter- 

 . clockwise direction. The author asks how the origin of the characteristic 

 rotation is to be accounted for, and his idea is that the sun has directly 

 induced in the flagellum an east-west rotary-like or whip-like propelling 

 movement. Experimental attempts to reverse or slow up the rotation 

 have not as yet yielded any result, but the author pleads for a considera- 

 tion of the idea that characters of a physiological nature may be 

 produced by environmental causes. Morphological characters, such as 

 strife, may arise in a similar manner, or through selection. By corre- 

 lation with the physiological characters, a cumulative and irreversible 

 effect is produced. J. A. T. 



British Fresh-water Rhizopods. — G. H. '^aile^ {Ray Society, 1919, 

 4, xii + 130, pis. 58-63, figs. 161-75). When the third volume of 

 this monograph was issued fifty genera had been described ; now by the 

 addition of Pyxidula, Capsellina, Diplochlamys, Microcorycia, BuUinuJa, 

 Cucurbitella, Averihtzia, Farmulina, and Plagio2)hrys, and the omission 

 of Ouramaha, the number is increased to fifty-eight. The volume deals 

 with the families Lobosa, Reticulosa, Vampyrellida, representing the 

 order Amoebina, and with the families Arcellida, Euglyphina, Gromiina, 

 and Amphistomina, representing the order Conchulina. A fine biblio- 

 graphical section has been contributed by Mr. John Hopkinson. 



J.A.T. 



Crystalloids of Entamoeba. — Armand Dehorne (Arch. Zool. 

 Exper., Notes et Revue, 1919, 58, 11-18, 1 figs.). In the amoeba 

 (Entamoeba dysenterise) which causes liver abscesses in man, crystalloids 

 are formed in the vacuoles of the endoplasm. They last only for a short 

 time, being much reduced or having disappeared when the cyst envelope 

 is completed. In fact the production of the crystalloids may be regarded 

 as a stage in the formation of the cyst envelope. Perhaps the same is 

 true of the trichocysts in Inf usorians. In general terms, the crystalloids 

 are chromidial in character, and every chromidial apparatus has to do 

 with shell-making, whether for isolation or protection. J. A. T. 



Reversion of Orientation to Light in Spondylomorum quater- 

 narum.— S. 0. Mast (Jouni. Exper. Zool., 1918, 26, 503-20). This 

 colonial Flagellate of sixteen cells is negative in its relation to light under 

 certain conditions, and positive in others. Reduction in alkalinity, 

 increase in anaesthetics, increase in temperature, and decrease in illumina- 

 tion, all have the same effect on orientation, making negative specimens 

 to become positive. The reversion is probably due to some specific 

 change in the physiological processes of the organism. What these 

 processes are is not known. They may involve electrical tension and 

 polarization, or permeability or absorption. Reversion depends upon the 

 time-rate of change in the concentration or intensity of the effective 

 factors in the environment, but it has not been demonstrated that it 

 depends on the time-rate of change in the physiological processes which 

 are involved in reversion. J. A. T. 



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