No. 2.] THE DEVELOPMENT OF THE NEWT. 307 



migration that permits the rearrangement of the pigment 

 on the surface of the egg. It is not tlierefore altogether 

 unwarrantable to suppose that the disturbing influence of 

 the nucleus may account in part at least for the existence 

 and position of the outer pigment ring. After the nucleus 

 leaves its peripheral position, but not before, the pigment 

 becomes uniformly distributed over the surface. The nature 

 of this repellant influence, if we choose to regard it as such, 

 must for the present remain obscure. It is sufficient to re- 

 member that similar phenomena, viz., the attraction of small 

 particles into close proximity to an object and the repul- 

 sion of other like particles to a distance, are not wholly 

 unknown. 



The massing of the pigment at the poles of the spindle 

 would seem to indicate the presence there of attracting bodies, 

 and I was therefore led to search quite carefully for centro- 

 somes, but without success. 



The spindle in all the eggs of this stage lies close against 

 the periphery of the Q'gg (Figs 18-22). There is sometimes 

 a slight depression in the surface of the ^^^ at the bottom 

 of which lies the spindle (Fig. 21), but this would seem to 

 be the exception rather than the rule. 



The axis of the spindle in thirteen oviduct eggs was ap- 

 proximately radial ; in two it was tangential. Schultze ('87) 

 has advanced an ingenious explanation of this varying dis- 

 position of the spindle axis in the ripening eggs of Siredon. 

 He considers in brief, "dass auch hier die abwechselnde 

 Einstellung der Spindel kurz gesagt aus dem Kampfe 

 zwischen dem karyokinetischen Gesetz und dem Gesetz der 

 Kernstreckung hervorgeht." For a searching discussion of 

 this interesting question I must refer to his analysis. 



I am unable to determine with certainty from my prepara- 

 tions the precise time of expulsion of the first polar body, since 

 I have not succeeded in discovering a polar body on the surface 

 of the oviduct ^%g. There is, however, a certain amount of 

 circumstantial evidence which appears to indicate that the first 

 polar body may be formed while the eggs are in the upper por- 

 tion of the oviduct. Eggs from the body-cavity and from the 



