MUSEUM OF COMPARATIVE ZOOLOGY. 453 



tached from the metamorphosed rodlike body, for the latter ultimately 

 disappears entirely by this process. The granules assume a circular 

 arrangement (I will speak of them as the circle of granules). Hertwig 

 is unable to say positively whether the whole of the other (larger) por- 

 tion of the nucleolus remains in the germinative vesicle, since many 

 preparations favor the view that particles of this portion now make 

 their way into the homogeneous spot of the protoplasmic knob. It at 

 least finally disfi^ppears, as does also the membrane and later the 

 " Grundsubstanz " of the germinative vesicle. 



What becomes of the " circle of granules " Hertwig unfortunately does 

 not state ; also the origin of the second stellate figure and the spindle 

 fibres that unite them cannot be considered as satisfactorily explained 

 by these observations. 



During the disappearance of the smaller nucleolar body, as seen in 

 living eggs, and soon after the debut of the first small radial figure, there 

 appears a second like figure near the first. In using acetic acid it is 

 seen that there lies between these two stellate figures a fibrous body 

 whose fibres become more distinct as the remnant of the nucleolus disap- 

 pears. This body ultimately forms the ''Richtungsspindel." The latter 

 elongates and takes a radial position, while the asters increase in size. 



Just what relation the " circle of granules " sustains to this spindle, 

 I am unable to discover. It is a difiicult point that needs to be defi- 

 nitely settled. Perhaps the conclusion nearest at hand is that the fibres 

 of the spindle are formed from the outer and larger part of the nucleolus; 

 that the inner corpuscle of the nucleolus furnishes directly, in the "circle 

 of granules," the equatorial zone of thickenings. But apparently irrec- 

 oncilable with this supposition is the fact that the "circle of granules" 

 occupies the centre of the first star, and that the second star arises near 

 (not by a division of) the first. 



The more general conclusion,* and one of fundamental importance, 

 which Hertwig reaches in his preliminary paper ('77", p. 273), seems in 

 the main just, and it is greatly to be regretted that he was not able to 



* " "Wenn ich die geschilderten Befunde deuten soil, so scheint mir ein unverkenn- 

 barer Zusammenhang zwischen dem Auftreten der beiden Strahlensysteme und der 

 Umbildung des Keimflecks der Art zu bestehen, dass bei der Auflosung des Keimblas- 

 chens die Kernsubstanz in das Protoplasma iiberwandert und an dem Orte, wo sie 

 sich zu dem Spindelformig difFerenzirten Kern ansammelt, erst ein und dann das 

 zweite Strahlensystem hervorruft. In erster Linie ist bei dieser Umlagerung der ac- 

 tiven Kerntheile der in der Vacuole des Keimflecks eingeschlossene kuglige Korper 

 betheiligt. Aber audi von der einhiillenden Kernsubstanz gelien offenbar Theile, 

 wenn nicht Alles, in das neue Kerngebilde mit iiber." 



