> ir. /;. hukh>un—Matiir<nioti of the Eyg of the White Jlouse. 



mat unit i..i. spiiiill.'. as observed by Rubnsclikin (:05) in the egg of 

 tilt" j;uiiu':i |>i£r, a.id by van der Striclit (-.06) in the egg of V. noctula, 

 but tlie di'tfrminini; ( luiracteiistic is its chromatin content. The 

 24 uiiivak'iit chromosomes (Text-tig. 9) resulting from the split- 

 ting Iciiglhcu (Mil int.) lilaments of various sizes, the form of which 

 furnishes a certain means of distinguishing this spindle from the 

 first i>olar spin<llf. These chromosomes sometimes lie with their 

 axes par.dh'l. but are generally ju'rjtendicular to that of the spindle, 

 as notrd by van der Stricht (:06) in the egg of V. noctula. 



The achntmalic fibers comjtosing the second polar spindle usually 

 come to a more or less sharj) focus, where centrioles have commonly 

 l.ft-n oliscrvt il, niadi' up of one or more eccentrically placed granules, 

 ill a lew instances radiating fibers have been seen by the writer at 

 uiic. viiy rarely at both jioles of this s])indle (PI. V, fig. 10). 



If 



o 



V CD 



FiK'ire 9. — Diagram of the twenty-four univalent chromosomes in the second 

 polar spindle of the ovarian egg shown iu PI. IV, fig. 7. 



Ilultrecht (:02) has observed centrioles in the second maturation 

 spindle of Tarsius npectrum, and van der Stricht (:o6) has described 

 both centrioles and aster fibers in both the maturation spindles of 

 V. noctula. 



A few ovarian eggs of the mouse show the first polar body at the 

 opj)osite pole of egg from the second maturation spindle, as observed 

 by Gerlacli (:o6), who interprets such cases by assuming that the 

 spindle lias moved alxnit in the egg. This hypothesis, however, 

 seems loss probable than that the polar body has been moved around 

 by jiressure upon the zona, and an examination of a number of eggs 

 similar to those siiown by (ierlach (:o6) in his fig. 18, has failed to 

 reveal a single instance where the spindle does not lie at right angles 

 to the radius of the egg ; which fact hardly supports the migration 

 theorv. 



