ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 213 



zone, we shall find in them a welcome elucidation of conditions such 

 as have only been guessed at in the case of other Amoehce. 



" In the sarcode body more and less fluid constituents are 

 present ; the former we find at the spots which betray a centrifugal 

 movement whether in the pseudopodia or in the advancing part of the 

 flowing AmoebEe (A. quadrilineata, villosa, tentaculata, &c.). The 

 heavier constituents remain behind and are dragged along, and we 

 see them finally break into many cushion-like processes of hyaline 

 protoplasm. 



" The pushing forward of the more fluid constituents is efiected 

 by the action of pressure upon the opposite side ; this is produced by 

 the outermost layer of protoplasm at this part acquiring a tougher 

 consistency by extraction of water. The latter is widened during the 

 flow of the Amoeba at the posterior end by all sorts of processes, 

 lobes, hairs, &c., which often give the Amoeba a peculiar aspect and 

 have led to the establishment of distinct species. The sarcode here 

 becomes so tough that as the Amoeba hastens forward it is drawn into 

 threads, if the expression may be allowed. 



" If the direction of movement is reversed the previous posterior 

 extremity begins to flow, and the most tenacious protoplasm occurs 

 on the opposite side. These conditions may be equally well studied 

 on the lobate pseudopodia, as also during the retraction of the 

 pseudopodium on the surface of which all sorts of humps and folds 

 are produced. 



" A tougher cortical zone of this kind is actually to be seen in 

 the forms here under consideration. When there is a centripetal 

 pressure acting uniformly it surrounds the whole Amoeba like a 

 membrane ; if the pressure ceases on all sides the Amoeba flattens into 

 a disk, the cortical zone liquefies and flows into a clear border of 

 more fluid sarcode, but if the pressure acts on one side the liquefaction 

 takes place only on the opposite side, and the mode of movement 

 which may be called the flow of the Amoeba is produced. 



" In the formation of individual pseudopodia (see A. tentaculata) 

 it is only a few spots that are subjected to these conditions, and in 

 accordance with this the tougher cortex dissolves only at certain points, 

 making way for the issuing softer sarcode." 



Protozoa of the White Sea.*— C. Gobi gives a sketch of Professor 

 Cienkowski's report on his expedition to the White Sea, which appears 

 in the 'Proceedings of the Natural History Society of St. Petersburg' 

 in the Eussian tongue, and is illustrated with three coloured plates. 



The sea was by no means rich in microscopical organisms, but 

 still a few new and interesting forms were found, and are described 

 and figured, such as Wagneria mereschhowskii, a new genus and 

 species of Protista, somewhat between Haeclcelina and ClathruUna ; 

 several new Flagellata, Multicilia marina nov. gen. et sp., having a 

 protoplasmic body of protean form without nucleus or contractile 

 vesicle, but having several cilia ; Exiiviaella marina, also new, with 

 an ovum-like body, flattened horizontally at the top, with two cilia 

 and one or two round marks (Schildchen) ; Daphnidium boreale nov. 

 * Cf. ' Nature,' xxv. (1882) p. 328. 



