Fig. 3, a-r: Stages of meiosis from squash preparations of pollen mother cells of Allium triquetrum, stained in Feulgens. a, leptotone; b, pachytene; c, diplotene; d, diakinesis of prophase I. Notice the characteristic “beaded” appearance of the synapsed chromosomes in b; the desynapsing chromosomes of c with chiasmata; the 9 compact bivalents in d. In e, metaphase I, the chromatin adjacent to the centromeres (arrows) is markedly drawn out from the chiasmata. f-h, anaphase I. Notice the different forms cf bivalents which can be interpreted according to the number and positions of the chiasmata in each. In g, the chiasmata have been lost (see Fig. 7) except that of the right hand bivalent (upper arrow): also note the widely separated chromatids of each chromosome (lower arrow). i, telephase I. In j, interphase, the new cell wall separating the nuclei is clear; also note the original parent cell wall. k, prophase II; l, metaphase II; m, one diad at metaphase II, the other anaphase II; n-p, anaphase II; q, telophase II with beginnings of cell plate formation; r, tetrad of pollen grains before liberation from the parent cell wall. a-g have been squashed during preparation to show the relevant features more clearly. Nucleoli are not visible as they do not stain with Feulgens.