8G8 Dr. H. E. Zicgler on Amitotic Nuclear Division 



nutritive cells of this kind in the terminal chamber of the 

 ovaries of different species of bugs Korschelt * has observed 

 the figures of amitotic nuclear division. 



In the follicle epithelium which envelopes the ovum of the 

 mole-cricket (" le tapis cellulaire qui recouvre I'oeuf de la 

 taupe-grillon arrive a I'etat parfait ") Carnoy f saw amitotic 

 nuclear division and multinuclear 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-cell becomes fully ripe, the biolo- 

 gical conditions which we have empliasized 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 with this division of the nucleus probably never occurs 

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

 find an indication of cell-division ; " 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 fluid 

 which surrounds the embryo, cannot at present be deter- 

 mined. 



In Cyclas cornea (a small freshwater mussel) I have 

 observed a striking enlargement and peculiar fragmentation 

 in the nuclei of the 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 ei'sten Eutwicklungsvorgange im Fliegenei,' 

 Zeitschr. f. wiss. Zoologie, Bd. 46, 18S8. 



* Korschelt, " Ueber die Entstehiing und Bedeutungder verschiedenen 

 Zellenelemente des Insektenovariums," Zeitschr. f. wiss. Zoologie, Bd. 43, 

 1886. 



t J. B. Carnoy, " La Cvstodi^rese chez les Arthropodes," La Cellule, 

 t. i., 1884, p. 219. 



X Blochmann, " Ueber direkte Kernteiluug in der Embryonalhiille der 

 Skorpione,'" Morphol. Jahrbuch, x. Bd., 1885. 



§ H. E. Ziegler, " Die Entwicklung vou Cydas cornea," Zeitschrift 

 fiir wiss. Zoologie, 41 Bd., 1885. 



