448 SUMMARY OF CURRENT RESEARCHES RELATING TO 



is ncitlicr a cell nor a cell-complox, but the product of several cells. 

 The homology between the ova of various animals is consequently to 

 be souglit for in the fact that the mature ovum always represents a 

 germinal mass, which contains all tlie elements necessary to future 

 development, and is the product of the activity of those cells which 

 have taken part in its construction. 



Marine Hemipterous Insect, iEpophilus Bonnairei.* — M. R. 

 Kuhler describes the rare marine hemipterous insect, ^jHqjhilm 

 Btmna'irei Signoret. The presence of eggs in the form described by 

 Signoret as the male, shows that this observer reversed the sexes in 

 his description. The female bears the genital armature on the ventral 

 surface, the male on the dorsal. 



y3. Myriopoda. 



Nerve-terminations on the Antennae of Myriopoda. f — M. B. 

 Sazepin describes iu detail the sensory hairs which are found upon 

 the antennas of Myriopoda as well as the nervous structures connected 

 with them ; they differ more or less in form in the different genera, 

 and the main varieties are depicted iu the plates which illustrate the 

 memoir. 



S. Arachnida. 



Direct Nuclear Division in the Embryonic Investments of 

 Scorpions.:}: — Dr. F. Blochmaun has been enabled to study a gravid 

 scorpion from Brazil, the cells of the coverings of the embryo of which 

 were of colossal size; the nuclei of the cells were large, and the pro- 

 toidasm was thicker around them than in other parts of the cell ; the 

 boundaries of the large cells were remarkable for being fibrillated. 

 In the resting condition the nuclei do not exhibit any remarkable 

 characters ; there is a rather coarse nuclear plexus in which one or 

 more irregularly formed nucleoli are to be found ; most of the cells 

 contuin two nuclei. Some of these may be seen to be elliptical in 

 lormj or to present the first signs of division ; but in them the con- 

 tents are not different to those of other cells. Division first becomes 

 apparent when there is a constriction of the nucleus ; this is always 

 median, and gradually becomes deeper, without the contents exhibiting 

 any changes. The nuclear plexus has just the same coarse network 

 as in nviclei which have and have not divided. The bridge of 

 substance which connects the two halves of the nuclei becomes 

 gradually thinner and thinner ; the filaments finally break, and w^e 

 have two separate nuclei. No cell-division appears to be associated 

 with this division of the nuclei. 



The process here described has a close resemblance to other cases 

 of direct nuclear division ; that of leucocytes may especially be cited. 

 Direct division is more common among plants ; as, for example, in 

 the Siphonocladiacefe, where there are multinuclear cells, the nuclei 

 of which in the anterior part divide with distinct differentiation of 

 their contents, and iu the posterior part by direct constriction ; in the 



* Coraptes Eendus, c. (1885) pp. 12G-8. 



t IMe'iu. Acad. Imp. St. Petersburg, xxxii. (1884) pp. 1-20 (2 pis.). 



X INIorpliol. Jahrb,, x. (1885) pp. 480-4 (1 pi.). 



