20 DUBLIN 



traced to a late stage in the development of the embryo, and 

 in every case where the individual chromosomes could be 

 studied they appeared in a form quite like that found in the 

 earlier cleavages. The same condition prevails in the divisions 

 of the tissue cells. An instructive comparison can here be 

 made. Fig. 103, PI. Ill, shows a cross section through a 

 " liver cell " in the metaphase. Both the cell and the chromo- 

 somes are remarkably like what was found in corresponding 

 division figure of the early oogonium (Figs. 62-63). The 

 chromosomes are all distinct V's, and are turned toward the 

 spindle. These spht longitudinally and are in the late anaphase, 

 and finally in the telophase, still V's (Fig. 104, PI. III). Here 

 they are of about the same size and form as those observed in the 

 last oogonial telophase (synapsis) (Fig. 66) but in the former 

 case the number is very clearly double that in the latter. 



Returning to the ovogenesis, it must be admitted that the 

 evidence is not as complete in the Q:gg as it was in the sperm ; 

 yet there can be but little doubt that the reduction is here at- 

 tained in a like manner, i. e., by an end to end conjugation of 

 the individual chromosomes in the last oogonial telophase. 

 There is then, at the very beginning of the oocytic period, a 

 known constitution of the chromatin, making possible a proper 

 interpretation of the processes which now ensue. 



The newly formed oocytes are now easily distinguished and, 

 in every regard, but size, resemble the youngest spermatocytes. 

 The chromosomes show the same polarity and the nucleus is 

 situated in like manner in reference to the cytoplasm (Figs. 

 67-69). Occasionally one or even two of the chromosomes 

 move away from the rest to the other end of the nucleus, but 

 as a rule, the apices are all directed away from the plane of the 

 last division, i. e., from the central tnd of the cell (Montgomery, 

 '99). At this, the earliest period of oocytic growth, the 

 angles of the V's are large. One may however observe an oc- 

 casional crossing of the distal arms to form loop-shaped figures 

 (Figs. 70-71), but to this little significance can be attached. 

 There is, at every point, confirmation of Montgomery's conten- 

 tion that the arms of the bivalent chromosomes are not sister- 



