. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. toward the observer, as sometimes happens (Figs. 237-239). Figure 192 shows four riugs seen from the edge and two from the side. The four chromosomes of a group may be arranged in a square rather than in a circle (Plate IV. Figs. 175, 176). The division of the rings may present different appearances according to the position of the chromosomes with reference to the poles of the spindle. The group may be a square, with one side turned toward each pole of the spindle (Diagram 2), or it may be more diamond-shaped (Diagra
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. toward the observer, as sometimes happens (Figs. 237-239). Figure 192 shows four riugs seen from the edge and two from the side. The four chromosomes of a group may be arranged in a square rather than in a circle (Plate IV. Figs. 175, 176). The division of the rings may present different appearances according to the position of the chromosomes with reference to the poles of the spindle. The group may be a square, with one side turned toward each pole of the spindle (Diagram 2), or it may be more diamond-shaped (Diagram 1) with an angle directed toward each pole. In either case division takes place as indi- cated by the dotted line, and the chromo- somes a and b go to one pole, c and d to the othei\ The final result, therefore, is the same as before. But in the first case the chromosomes a and b, still held to- gether by liuin threads, move toward the pole maintaining imchanged their relative positions, i. e. the rod with a chromosome at either end remains at right angles to the polar axis of the spindle, and is therefore in proper position for the second division, which follows di- rectly upon the first, and is at right angles with it, a going to one sper- matid, b to the other. By the second mode the pair o, b starts for the pole, either in a very oblique position or nearly parallel to the polar axis, and with a in advance. It therefore must turn 45° or more so as to be in the proper position for the second division. The later stages of the first spermatocyte division are shown in Plate III. Figs. 112, 113, 117, 118, 122, and 123, which are drawn from preparations stained with safranin and victoria-green, or by Henneguy's method. These methods do not bring out the individual chromosomes at this stage. Figures 118 and 122 show the interzonal filaments still bridging over the space between the already separated cells. Some cells at this stage (Figs. 113, 117) have a peculiar appearance, as
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