228 C. O. WHITMAN. 



piieustes and mouse), |4 Hertwig (|L' , Echinus and frog), Stras- 

 burger ('5% Piiaseolus multitioru;?), and Fol (-^4), Asteriass), 

 leave little room to doubt that this reticulum is characteristic of 

 old nuclei in general. The nucleus represented in fig. 6L is a 

 stage reached after a comparatively long period of rest in the 

 cleavage-activity — a stage which precedes only by a short time, 

 as we shall st-e ht^reafter, the process of division. This nucleus 

 shows no trace of a membrane, and the anastomosing rays of 

 the nucleo-plasm are continued directly into the protoplasm of 

 the surrounding yolk. That this is a veritable condition of the 

 living nucleus, and not a deceptive appearance produced by re- 

 agents, as Bischoff {yj) is inclined to believe, is evident from the 

 fact that it is to be seen in living nuclei, according to the testi- 

 mony of Hertwig (^t)> Kleinenberg, and others. 



(/;) ArcMamphiaster. — The next stage in the history of the 

 germinal vesicle, of wdiich I have any accurate knowledge, is 

 that of the bi-stellate fiirure (karyolytic figure, Auerbach ; 

 *' Amphiaster de rebut," Fol) which I will designate as archi- 

 amphiaster, to distinguish it from the later amphiasters directly 

 concerned in the cleavage. 1 have succeeded in obtaining only 

 eight or ten sections which show both poles of this amphiaster 

 — most sections cutting the figure obliquely. The axis of the 

 archiamphiaster is generally inclined 20° to 45° to that radius 

 of the egg which passes through its centre (fig. 62). In later 

 stages it is much less, or not at all inclined (fig. 63). The most 

 conspicuous {)arts of this figure are the two poles encircled with 

 well-defined radial lines. These lines can be traced to a con- 

 siderable distance beyond the polar areas out into the densely 

 packed yolk-spheres. Their point of convergence is the centre of 

 the polar areas. This central part of the area (strongly shaded 

 in the figure) is deeply coloured with carmine, and contrasts 

 strongly with the rest of the area which is much less deej)ly 

 stained. Fig. 64 represents one of these polar areas with its 

 radial lines more highly magnified. Between the two poles is 

 a more or less spindle-shaped area free from the yolk-spheres. 

 This area corresponds very nearly in size with the germinal 

 vesicle of the previous stage. Within this space the radial lines 

 of the two stars ( = polar area ])lus radial lines) meet, thus 

 becoming continuous from j)ole to pole. These inter-stellate 

 lines (" Kernfasern," or " Spindlefasern,'' Strasbnrger and Biit- 

 schli ; "filaments bipolaires" or " intranucleaires," Fol) do not 

 present themselves here in so conspicuous a form as they seem 

 to in the eggs of plants and many animals. They appear to 

 differ in no essential way from the other radial lines. In only 

 two preparations have 1 found anything in the ecpiatorial zone 

 of these lines at all comparable with the ihickencd portions 



