204 BULLETIN OF THE 



amphiaster. Aside from the fact that the egg in a living condition was 

 under observation at least some ten minutes immediately prior to its im- 

 mersion, during which time one could hardly have failed to distinguish 

 a fully formed first polar globule, had such actually existed, there are 

 other and sufficient reasons for construing the observations diiferently. 

 Not only that the comparatively large size of the polar globule points 

 to its being the first, rather than the second, and that a slight prolonga- 

 tion from one side (p) is evidence that it had not yet wholly severed its 

 connection with the vitellus, but it is especially the evidence within the 

 vitellus itself that makes the above interpre^tion inadmissible. 



This can be understood only by reference to what will appear more 

 fully in speaking of the amphiaster of the first cleavage sphere ; namely, 

 that the two stars of the cleavage amphiaster lie in a plane which is 

 perpendicuar to the animal radius at a point much nearer the animal 

 than the vegetative pole, and that they are of almost identical appear- 

 ance, though often deviating considerably from a spherical form. (Com- 

 pare Fig. 82.) 



None of these conditions are fulfilled by the figure under considera- 

 tion. There is no evidence that any one of the lines perpendicular to 

 the axis of the spindle at its middle * terminates at the animal pole of the 

 vitellus ; and even if such evidence existed, the plane, which is perpen- 

 dicular to such line and also passes through both the asters, would not be 

 perceptibly removed from the centre of the vitellus. Moreover, while 

 the two stellar masses are almost spherical, — and therefore unlike that 

 which we might expect in the amphiaster of the first cleavage sphere 

 (compare Fig. 82), — they differ from each other in the sharpness of 

 outline already noticed, and thereby again fail to conform to the re- 

 quirements of the indicated interpretation. Other objections, drawn 

 from a comparison of this figure with the amphiaster of the first cleav- 

 age sphere, might be adduced in answer to the possibility of this ex- 

 planation ; but enough has been said already to place beyond doubt its 

 true nature ; it is the amphiaster that immediately precedes the forma- 

 tion of the second polar globule, f 



* It is at once apparent from the figure that no such perpendicular could be a radius 

 of the vitellus, from the fact that one end of the spindle is much farther from its cen- 

 tre than is the other. 



t The possibility that one of the stars might be due to fecundation — might be the 

 so-called male aster — has not been overlooked. But the intimate union of the two 

 stars by means of a spindle which has an equatorial zone of granulations would make 

 this extremely improbable, even if the method in which the two pronuclei become 

 joined were less accurately known than at present. See pp. 224-229. 



