158 W. H. LONGLEY 



Eggs may attain to this stage and degenerate in the ovaries of 

 sexually immature animals, or may do so after the formation of 

 a first polar spindle, or with the first polar body and second matur- 

 ation spindle. In sexuallj^ mature animals kept from pairing 

 during a period of heat, degeneration may also intervene at anj' 

 of the stages just indicated, but the actual nuclear changes 

 appearing in this futile maturation are subject to a delay not 

 manifested in eggs undergoing maturation normally in the ovaries 

 of animals allowed to pair. 



The first polar spindle 



It has been noted already that the germinal vesicle in preserved 

 material does not lie in any constant position with respect to the 

 deutoplasmic accumulation within the egg. Similarlj'- it is ob- 

 served, as might be expected, that in the same kind of material 

 the first polar spindle lies at either pole of the egg, or at any inter- 

 mediate peripheral point. R. Van der Stricht ('08) has observed 

 the same phenomenon. 



This spindle seems to be organized from the contents of the 

 nucleus at a variable period between twenty and fifty hours after 

 pairing. It is found perpendicular to the surface of the egg (fig. 

 8) and there is no evidence that it occupies a preliminary para- 

 tangential position as in the mouse (Tafani) and guinea pig 

 (Rubaschkin). In this respect it agrees with the spindle of the 

 bat's egg (Van der Stricht). 



In thirty-three ovaries obtained from nineteen different ani- 

 mals, not one first polar spindle was found in an egg which ap- 

 peared normal. This fact would seem to indicate that the first 

 spindle discharges its function speedily. In this respect it is in 

 sharp contrast with the second spindle which does not proceed 

 to divide until the sperm head enters the egg. If it is true that 

 the whole process of formation of the first polar spindle is consum- 

 mated in a brief time, then it follows that the period during which 

 a spindle might lie parataiigentiall}^ must be still more brief 

 and this fact maj- explain the failure to discover any spindles in 

 that condition. 



