330 THOS. H. MONTGOMERY, 



spindle their number can best be counted, but this is not easily done 

 on account of their irregular form and dense grouping. By carefully 

 drawing all the chromosomes in a number of nuclei, and then counting 

 the chromosomes upon the drawings, the following results were ob- 

 tained, giving the number for each nucleus separately: 14, 14 or 15, 

 14, 14 or 15, 14 or 15, 13, 14, 14, 14 or 15, 13 or 14, 14 or 15, 

 16 (?), 14, 14, 14. Thus the counts varied from 13 to 15, in one 

 doubtful case 16; in those cases where the chromosomes could be 

 most favorably counted (Figs. 187, 188, pole views), it was found to 

 be 14; and accordingly it would appear practically certain that the 

 number in the 1st maturation monaster is 14. This ist just half the 

 number of the chromosomes found in the spermatogonic divisions. The 

 figures (camera drawings) show how greatly the volume of the in- 

 dividual bivalent chromosomes of the same plate varies. 



The cell body during the prophases has undergone considerable 

 changes. In the preceding rest stage it showed a distinct polarity : a 

 distal pole, marked by a large accumulation of yolk and cytoplasm, 

 can be readily distinguished from a central pole, where the nucleus 

 lies (Figs. 99, 101, 103, 104, 106, 108—111, Plate 20). To follow 

 the subsequent changes in form undergone by the cell body it is best 

 to study those spermatocytes which lie free in the fluid of the seminal 

 vesicle, since there the cells are to least extent subject to mutual 

 pressure. When the two pairs of centrosomes reach opposite points 

 on the surface of the nucleus, and are the centres of well-marked 

 cytoplasmic radiations, the cell body has a more truly spherical form, 

 and the yolk globules are arranged in a layer close to the cell mem- 

 brane (Figs. 168, 169, Plate 22). At the time of the complete mon- 

 aster stage, the yolk globules are all placed in a single layer at the 

 periphery of the cell, pretty evenly distributed along the whole inner 

 surface of the cell membrane (Figs. 179 — 182), and no longer as be- 

 fore mainly at the distal pole of the cell. Thus sinmltaneously in the 

 cytoplasm we find the formation of astral radiations, the rounding off 

 of the cell body, the gradual disappearance of the idiozome mass, and 

 the rearrangement of the yolk. This coincidence might lead one to 

 consider that the pole radiations are in some manner responsible for 

 the movements of the yolk and the rounding of the cell body (Figs. 161 

 —165, Plate 21; Figs. 166—169, 175, 176, 179—182, Plate 25). But 

 since at later stages cell movements are clearly marked, as well as 

 further rearrangements of the yolk globules, it might seem more prob- 

 able that these movements are due to a flowing or current of the 



J 



