494 SUMMAEY OF CUREENT JIESEARCHES RELATING TO 



stroyed, and that it does not reappear until a new membrane is formed 

 around tlie daughter-figures. During mitosis there is a much closer 

 connection between cell-body and nucleus than when the nuclei are at 

 rest ; this is probably due to the intermixture of the nuclear material 

 with the interfilar mass. Particular attention is directed to the influence 

 of preservative reagents on the characters of the cell. 



Nerve-cells in Birds.* — Sig. E. Falzacappa has investigated the 

 origin of the nerve-cells and the minute structure of the central nervous 

 system in birds. His observations led him to the following conclu- 

 sions: — (1) there is in the embryonic state an entire absence of the 

 polygonal nerve-cells, but the primordial cells are identical with those 

 of the neuroglia of the adult ; (2) cells arise from the primitive elements 

 by gemmation, after the fashion of a Nostoc chain ; (3) these new cells 

 are gradually transformed into the free polygonal elements ; (4) the 

 nuclei of the primordial cells resemble those of the adult neuroglia ; 

 (5) the primitive cells furthermore respond to reagents in the same way 

 as the neuroglia or the perfect polygonal cells. The primordial cells of 

 the embryonic brain are therefore neurogenetic, giving rise to the 

 special nerve-cells. The author proceeds to bring forward detailed 

 histological evidence in support of the conclusion that the specific 

 nerve-cells have the same nature as those of the neuroglia. Plates are 

 promised in a completed memoir. 



Form and Size of Red Blood-corpuscles of Adult and Larval 

 Lampreys.f — Mr. S. H. Gage has examined the red blood-corpuscles of 

 the lampreys of Cayuga Lake. The varying statements made with 

 regard to these cells give an interest to his observations. Wagner, in 

 1838, described the circular outline of these cells, and he, with Kolliker 

 and others, have noted their biconcave character. Gulliver and Giinther 

 state that they are flat or biconvex, and neither Gegenbaur nor Wieders- 

 heim draw attention to their peculiarities ; Shipley and Thompson have 

 asserted that the blood-corpuscles of the larvae were oval and of the 

 adult circular. Mr. Gage finds that the red blood- corpuscles of both 

 adult and larval lampreys are circular, biconcave, nucleated discs ; the 

 observation that they run into rouleaux, like those of all Mammals, 

 except the Camelidse, appears to be new. 



y. General. 



Fresh-water Fauna of East Africa.^ — Dr. F. Stuhlmann has a pre- 

 liminary report on his investigation of the fresh-water fauna of East 

 Africa. The Ostracoda are well represented, both by species and indi- 

 viduals, and there appear to be some very remarkable forms among them. 

 The Oligochteta — Perionyx, Eudrilus, and Digaster — are very numerous; 

 there are several species of Nais, and a large number of Dero ; a new 

 species of ^olosoma was found in enormous quantities. Turbellarians 

 appear to be scarce. Of Nematodes some small forms of Rhabditis are 

 reported. Conochilus volvox is very common. A small clear greyish- 

 green Hydra with five arms was observed. The Protozoa are very 

 numerous, there being quite a series of Rhizopods, several species of 

 Vorticella, &c., and a number of Flagellata. 



* Bull. Soc. Nat. Napoli, ii. (1888) pp. 185-93. 

 t Proc. Aiuer. Soc. Micr., x. (1888) pp. 77-83, 

 X SB. K. Akad. Wiss. Berlin, 1888, pp. 1255-69. 



