272 



A. RICHARDS. 



Button (1900) was the first of a group of cytologists working 

 on the chromosomes of grasshoppers to point out that in the early 

 stages of nuclear formation each chromosome forms a vesicle 

 about itself, but thought that later the proximal ends of these 

 fused, a condition which he interpreted as supporting the idea 

 of chromosome individuality. His conception of a chromosome 

 is not unlike that of Conklin, and has since been amply confirmed. 



The occurrence of the chromosomal vesicles is quite common in 

 the eggs of animals, and it has also been reported in certain other 

 tissues as well. The following list is presented merely to give 

 a few examples; it is in no way complete, but will serve to show 

 the wide distribution of the phenomenon. 



Name, W. G. Von. 



Trans. Conn. Acad., 



Vol. X., 1899. 

 Goldschmidt, R., 



Zeit. f. wiss. 



Zool., Ed. 71, 1902. 

 Von Kemnitz, G. A., 



Arch. f. Zellf., 



Ed. 10, 1913. 

 Grille, K., Arch. 



f. Zellf., 12, 1914. 

 Boveri, Th., 



Merkel u. Bonnet's 



Ergebnisse, 1891. 

 Lillie, F. R., Jour. 



Exp. Zool., 12, 1912. 

 Mead, A. D., Jour. 



of Morph., 13, 1897. 

 Lefevre, G., Jour. 



Exp. Zool., 4, 1907. 

 Wilson, E. B., 



The Cell, 1900. 

 Boveri, Th., Zell- 



studien, IV., 1900. 

 Buchner, P., Arch. 



f. Zellf., 6, 1911. 

 Konopacki, M., Arch. 



f. Zellf., 1911. 

 Schaxel, J., Arch. 



f. Alikr. Anat., 



Bd. 76, 1911. 

 Bury, J., Arch. f. 



Entw., 36, 1913. 



Planorbis, early Figures vesicles in anaphases. 



development of 



eggs. 

 Polyslomum eggs. 



Branchy CKli 

 eggs. 



Gyrodactylus 



elegans eggs. 

 A scar is eggs. 



Nereis eggs. 

 ChcElo-pterus eggs. 



Thalassema first 



cleavage. 

 Toxopneustes egg 



cleavage. 

 Echinus eggs. 



Sea urchin. 

 Sea urchin. 



Strongylocentrotus 

 egg. 



Echinoid egg 

 cleavage. 



Karyomerites, at first one to a chro- 

 mosome; later fuse and are not 

 recognizable. 



Karyomerites which later fuse. 



Karyomerites which fuse later. 



Accidentally separated chromosomes 



produce vesicles, from which new 



chromosome arises. 

 Figures vesicles in telophase; later 



fuse in reconstruction. 

 Figures show what are probably 



chromosomal vesicles. 

 Vesicles in anaphases; later they 



fuse. 

 Figures vesicles in telophase. 



Figures vesicles in anaphase. 



Karyomerites in first partheno- 



genetic maturation division. 

 Vesicles produced experimentally; 



thinks of them as nuclear budding. 

 Vesicles in telophase; they fuse, 



then alveolize, producing fine 



nuclear network. 

 Karyomerites in early stages. 



