ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 323 



the rhizopodia are developed in the equatorial plane of the cell, which 

 itself is flattened-ellipsoidal to flat in form. But this circumstance is 

 certainly secondary, and seems to be an arrangement often realized, for 

 in consequence the cells can be grouped in one plane. The animal food 

 is caught in the net, but is also digested, constituting a high order of 

 apparatus. Ghrysarachnion is oligotlierm, and apparently is confined to 

 cold mountain-tarns. E. S. Gr. 



Rhizopodial Development of the Flagellatse. IV. Fusion-plas- 

 modia in Flagellatae, and their Significance in the Descent of 

 Rhizopods from Flagellatae. — A. Pascher (Archiv. Protistenk., 1916, 

 38, 31-64, 8 pis., 20 figs. See also Bot. Gentralbl, 1917, 135, 167-8). 

 Myxochrysis seldom develops swarmers ; it can also produce descendants 

 which have so far lost the characters of FlagellatEe — namely, chromato- 

 phores, characteristic cysts, special assimilation-products — as to be no 

 longer recognisable and to stand isolated. Rhizopodial formation is a 

 secondary acquisition, and the Rhizopods are derived forms, adapted to 

 an animal nutrition. E. S. G. 



Microplankton of Plymouth Sound. — Marie V. Lebour (Journ. 

 Ifariiie Biolog. Assoc. Plymouth, 1917, 11, 133-182, 2 tables and figs.). 

 Here are the results of a year's constant study of the microplankton of 

 Plymouth Sound from the region beyond the breakwater. Both the 

 flora and fauna were studied from samples collected every fortnight. 

 Besides the usual tow-nettings, water samples were taken, centrifuged 

 and examined ; and thus several minute organisms, which escape through 

 the meshes of the finest silk nets, were added to the records. A syste- 

 matic list of the organisms is given, and includes seventy-four diatoms. 

 This is followed by a survey of the plankton in each month, by the 

 weather records,' and by two tables showing (1) the average number 

 and relative abundance of each species in each week ; (2) the average 

 number of Diatomacese and Peridiniales in 1 c.cm. for each month. 



A. G. 



Peridiniales of Plymouth Sound. — Marie V. Lebour {Journ. 

 Marine Biolog. Assoc. Plymouth, 1917, 11, 183-200, 14 figs.). A list 

 including all the Peridiniales identified in the plankton captured 

 throughout a year from September 1915 to September 1916. New and 

 rare species of Gymnodiniacese are described and figured. In all sixty 

 species are recorded ; five of Gymnodinium, two of Spirodinium, and 

 one of Gochhdinium are new ; and twenty-eight are new records for the 

 Plymouth area. A. G. 



Nuclear Division in Euglena viridis. — B. Tschenzoff {Archiv. 

 Protistenk., 1916, 36, 137-173, 2 plates and figs. See also Bot. 

 Central hi., 1917, 135, 148). In Euglena viridis, the splitting of the 

 chromosomes takes place in the anaphase or telophase of the previous 

 division. The split chromosomes preserve their individuality through- 

 out the resting nucleus up to the metaphase, when they arrange them- 

 selves in pairs and then move off separately. Nuclear division in 

 Evglena follows none of the twelve types of the primitive mitoses for 

 protozoa-nuclei given by Alexeiefl^. E. S. G. 



