ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 31 



relatively to the others — a secondary effect of the displacement. There 

 is great mortality during the migration of the eye. The importance of 

 tlie paper is in its analysis of the factors actually operative in the moving 

 of tlie down-turned eye to the up-turned side. J. A. T. 



&. Histolog'y. 



The Neurone. — H. B. Ferris {Psychological Bulletin, 1918, 15, 

 257-63). A review of numerous recent papers on the neurone. L. S. 

 . Eoss regards the trophospongium of the crayfish (Gamharus) as a 

 nutritive and supporting, non-nervous framework extending in from 

 without. Ramon y Cajal believes that the Golgi net in cells of the 

 cerebral cortex represents a canalicular system filled with a lipoid-con- 

 taiiiing substance. It is noted by A. M. Pappenheimer that the Golgi 

 net has not been observed in the living cell, though it occurs in pre- 

 parations of most kinds of cells. Nissl-bodies are generally believed to 

 consist of a nucleo-protein containing iron, which is elaborated by the 

 nucleus. Some observers claim that they can see them in the living 

 cell ; others regard them as precipitation products. E. Y. Cowdry finds 

 that " chromophile " cells in the nervous system are usually shrunken 

 as a whole and as regards their nucleus ; the condition is not an 

 artefact, or pathological, or senile. M. Flesch finds abundant " chromo- 

 phile " cells in the Gasserian ganglion, larger than the normal cell, and 

 fewer in young than in old. M. E. and AY. H. Lewis observe that 

 mitochondria change in shape, size and number, and that they move 

 about and may pass from one cell to another. N. 0. Nicholson notes the 

 differences in the mitochondria of different cells of the central nervous 

 system of the white mouse. M. I)e (i. Thurlow believes that there is a 

 definite mitochondrial-cytoplasmic ratio. The evidence from various 

 sources seems to show that mitochondria are definite, discrete, formed 

 elements found in all kinds of cells, and at all ages, and are chemically 

 a lipoid albumen. They are not related genetically to the neurofibrils, 

 Nissl-bodies, or the Golgi net. They are connected with the funda- 

 mental metabolic processes that occur in cells, possibly with respiration. 



J. A. T. 



Motor Nuclei and Roots in Brain of Fishes. — C. .T. Van der 



HoRST {Tijdschr. Nederland. Dierlc. Ver., 1918, 16, 168-270, 16 pis., 

 37 figs.). An elaborate study relating to a great variety of types, 

 showing that the position of the motor nuclei and roots has often con- 

 siderable taxonomic value, and showing that their position and displace- 

 ment bear out, on the whole, the theory of neurobiotaxis — that the 

 main dendrites grow out towards, and the whole body of the ganglion 

 cell is displaced in the direction of the centre of stimulation, while the 

 axis-cylinder grows away from the centre of stimulus or the source from 

 which stimuli radiate. J. A. T. 



EflTect of Ions on Ciliary Motion. — J. Gray (Proc. Gamhridge 

 Phil. Soc, i;)20, 19, 313-4). A large number of experiments show that if 

 the concentration of hydrogen ions is only slightly greater than normal, 

 the cells (of mussel gills) can react to the environment, and recovery 



