344 MONTGOMERY. [Vol. XV. 



1894. 



Blochmann ('94) gives a preliminary account of the results 

 of the observations of Keuten ('95). 



Born ('94) investigated the maturation of the ovum of Triton. 

 In the " Urei " are one or several large, spherical nucleoli. In 

 the second stadium of the maturation (production and degenera- 

 tion of a " Chromatinfadenknauel ") there are at first ten nucle- 

 oli, then they become more numerous, increase in size, and 

 lie close to the nuclear membrane. In the third stadium (eggs 

 of from 200/X to 3SO/i in diameter) the nucleoli increase still 

 more in size. In the fourth stadium (eggs measuring from 350/x 

 to 8oo/tt, first appearance of yolk in the cytoplasm) most of the 

 nucleoli lie in the peripheral " Karyohyaloplasma," only a few 

 pale ones being in the center of the nucleus (this part of the 

 nucleus he terms " Centralkorper "). At the commencement 

 of this stage the nucleoli increase, at its conclusion decrease, 

 in number, and "wahrend der ganzen Periode steigt die Zahl 

 der verkleinerten und abgeblassten Nucleolen im Centralkor- 

 per," only a few of these pale ones being situated at the 

 periphery of the nucleus. Thus while at the beginning of this 

 period the nucleoli attain their maximum size, at its end most 

 of them wander towards the center of the germinal vesicle, 

 become smaller, and lose their staining power. Fifth stadium 

 (the nucleus passes to the periphery of the egg): the nucleoli 

 decrease still further in size, and continue to wander to the 

 center of the nucleus ; some of the larger ones contain vacuoles, 

 and for the first time appear granular ; the smaller, lightly 

 staining nucleoli are division products of the larger ones. At 

 the commencement of the sixth stadium (formation of the first 

 pole spindle) all the nucleoli lie in irregular rows around 

 the " Centralkorper," stain quite intensely, and are regularly 

 vacuolated ; the few in the midst of the " Centralkorper " are 

 smaller and stain more faintly ; when the nucleus has decreased 

 still further in size, all the nucleoli vanish at once. Born con- 

 cludes as follows : " Eine sichere Herleitung der peripheren 

 Nucleolen von den Nucleolen des Ureies, bin ich freilich nicht 

 im Stande zu geben. . . . Die Nucleolen stehen in Beziehung 



