DEVELOPMENT OF THE ALBINO RAT | 2H 
The phenomena of maturation and fertilization in the albino 
rat have been carefully studied by Sobotta and Burckhard, 
from whose account the following brief summary is taken: The 
behavior of the ovum of the albino rat with respect to the forma- 
tion of polar bodies is very similar to that of most other mammals 
studied. The first polar body is given off within the ovarian 
follicle, the second in the oviduct and only after semination. 
The first maturation spindle, developed from the nucleus of the 
oocyte of the first order, forms usually immediately after par- 
turition. Kirkham and Burr state “it is usually formed less 
than 24 hours after parturition.’’ It is short and broad, with 
the chromatin scattered. The first maturation spindle lies near 
the center of the ovum, then passes toward the surface assuming 
a tangential position, and only with the beginning of metakinesis, 
takes a radial position. The chromosomes of the first maturation 
spindle, estimated as numbering 16, appear in the form of modified 
rings, which ate divided transversely across to form short rounded 
rods with a longitudinal direction in the diaster stage. The 
first polar body is formed in the ovarian follicle and appears 
to be relatively large. It is evident only in the ovarian ovum, 
and appears to be lost soon after its formation. Its fate is 
doubtful. The first polar body is nearly always missing in tubal 
ova. Kirkham and Burr state that “the rare occurrence of 
the first polar body associated with the egg in the tube is to be 
attributed to its rapid disintegration, which begins as soon as it 
is formed, and may lead to complete disappearance before 
ovulation occurs.” The second maturation ‘division begins 
immediately after the completion of the first, without an inter- 
vening resting phase. The spindle formed is narrower and 
longer than the first, with the chromatin massed. In its monas- 
ter stage, it lies in a tangential position, with the chromatin 
in diads, and with the lines of division at right angles to the 
axis of the spindle. The appearance of the second maturation 
spindle in the monaster stage marks the end of the maturation 
phenomena in the ovary. The monaster stage of the second 
oocyte division was not observed in the ovary by Sobotta and 
Burekhard, but was seen by Kirkham and Burr. The first 
