I2O H. H. NEWMAN. 



spherical contours. Moreover the wrinkles occur chiefly on the 

 side of the nucleus toward the cell membrane to which is in 

 close proximity at this time. 



In follicular stage 10 the nuclei of ovocytes are in a condition 

 represented by Figs. 2"ja and b. These two drawings indicate the 

 entire chromatin content of a single nucleus. It will be noted 

 that the chromosomes are clearly denned but still massed in 

 groups. There is no distinguishable plasmosome. All of the 

 chromatin takes with equal avidity basic dyes and must therefore 

 be considered rich in nucleinic acid. There are only remnants of 

 the linin network in the form of scattering slender threads 

 running from the chromosomes to the periphery of the nucleus. 

 A number of these threads appear to converge at one point and 

 may indicate the first steps in spindle formation. Subsequent 

 stages deal with the actual maturation divisions. 



VIII. THE FIRST POLAR SPINDLE. 



The stages immediately preceding the establishment of the 

 complete cleavage spindle are difficult to find in sections, owing 

 probably to the great rapidity of the process. One of the few 

 stages that have come to light is shown in Figs. 280, and b. In 

 this case it is obvious that the spindle is forming, but chiefly at 

 one end. The chromosomes are very clearly defined and have 

 lost the tendency to be grouped into masses. There is a marked 

 difference in the size of the individual elements, some being many 

 times the volume of others. This is interesting in view of the 

 fact that in the fully formed spindle there is no marked size 

 difference among the chromosomes. The explanation of this 

 condition probably lies in the inequality of state of condensation 

 in the various elements. Numerous camera drawings of the 

 chromosome complex of this period have been made, and on the 

 basis of such drawings chromosome counts have been attempted. 

 It is extremely difficult, however, to get even approximately 

 correct estimates of the actual number of univalent and bivalent 

 elements present. It seems quite obvious from examination of 

 the figures that both single and double elements occur side by 

 side, and it is not always possible to distinguish one type from 

 the other. A study of Figs. 280. and b will reveal some elements 



