308 ])i". II. 1j. Ziivyler on Amitotic Nucliar Division 



nutritive cells of this kiu'l in tlie terminal chamber of the 

 ovaries <if different species of l)u;^s Korschelt * has oljserve 1 

 the figures of amitotic nuclear division. 



In the follicle epithelium vvh.ich envelopes the ovum of the 

 m<jle-cricket (" Ic tapis ceUulaire qui recouvre I'oeuf de la 

 tau|)e-grillon arrivd k I'^tat ]jarfait ") Carnoy f saw amitotic 

 nuclear division and niultinuclear cells. Since the cells of 

 the epithelium of the follicle play a great part in the nourish- 

 ment of the growing egg-cell, and since they lose their 

 importance when the egg-oell becomes fully vipe, the biolo- 

 gical conditions which we have emphasized above exist in 

 this case also. 



In the large nuclei of the external layers of the embryonic 

 envelo])e of a Brazilian scorpion direct division has been 

 observed by Blochmann |. " A division of the cell in con- 

 nexion witli this division of the nucleus probably never occurs 

 in any case." In none of his preparations did Blochmann 

 find an indication of cell-clivision ; " the absence of cell- 

 division is also attested by the large number of binuclear cells 

 which are found in all parts of the embryonic envelope." 

 " The embryonic envelope is a transitory structure, which 

 certainly undergoes disintegration soon after these divisions." 

 Whether this embryonic membrane has an important physio- 

 logical function, whether it perhaps secretes a serous tiuid 

 which surrounds the embryo, cannot at j)re3eut be deter- 

 mined. 



In Cyclaa cornea (a small freshwater mussel) I have 

 observed a striking enlargement and peculiar fragmentation 

 in the nuclei of tlie epithelium of the brood-pouches, which 

 arise in the gills and surround the embryos §. A fluid 

 gradually accumulates in the brood-capsules ; a secretory 

 function on the part of the cells is therefore rendered probable. 

 Certain of the epithelial cells separate from the wall and are 

 devoured by the embryos, which continue to grow within the 

 brood-capsules until they attain sexual maturity. 



toria iu Henking's paper " Die ersten Eiitwioklmisrsvorjran.'e iiu Fliegenei,' 

 Zeitschr. f. wiss. Zooloirio, Bd. 4(!, 18><8. 



* Korschelt, " Uebor die Knt^tebiiiiir und nedeutnn<rder verschieden«n 

 Zellenelemento des Insektcnoviirimns,'' Zoitsolir. f. wiss. Zooloirie. BJ. 4^3, 

 1886. 



t J. B. rarnov, " Lii C'vstoditH-ese chez les Arthropodes," La Cellule, 

 t. i., 1884, p. 21iV 



I liloclunaiin, " Ueber dirokte Koruteilung in der Embryoiialhiille der 

 Skoipionc," Morphol. Jiihrbm-h, x. 13d., 188.'3, 



§ 11. E. Zit'frler, " Die Eiitwicklung vou Ci/clas cornea,'' Zeitschriit 

 fiir wiss. Zoolugie, 41 Bd,, l88o. 



