A morphological study of some members of the genus Pallavicinia . to Leitgeb ([1], II,p. 44) these two peripheral cells do not extend to the top of the anther-idium, and a third peripheral cell is cut off before the separation of thecentral cell is complete. The appearance of longitudinal sections of theyoung antheridium, cut respectively in the plane of the first median wall,and at right angles to it, are shown in Fig. 10, D, G, E, H. Cross-sectionsof similar stages are shown in Fig. 11, A, C. The next divisions takeplace in the peripheral cells, and in the stalk, the two primary spermato-gen
A morphological study of some members of the genus Pallavicinia . to Leitgeb ([1], II,p. 44) these two peripheral cells do not extend to the top of the anther-idium, and a third peripheral cell is cut off before the separation of thecentral cell is complete. The appearance of longitudinal sections of theyoung antheridium, cut respectively in the plane of the first median wall,and at right angles to it, are shown in Fig. 10, D, G, E, H. Cross-sectionsof similar stages are shown in Fig. 11, A, C. The next divisions takeplace in the peripheral cells, and in the stalk, the two primary spermato-genous cells remaining undivided until the stalk is well developed and 22 GENUS PALLAVICINIA the four original peripheral cells of the antheridium have each divided atleast once (Fig. 10, G). The first division in the central cells is a transverseone, quickly followed by a vertical division, so that whether in longitudi-nal- or cross-section, the central cells are arranged quadrant-wise (, H, ii, B). The subsequent divisions follow rapidly, but without any. A-D. P. radiculosa; E-G, P. Levieri. A-C. Cross-section of young antheridia. D. Longitudinal section of a nearly ripe antheridium. E-G. Longitudinal sections; H, transverse section. METHODS 23 definite succession being evident. There is but little displacement of theoriginal division-walls, so that up to the last divison of the sperm-cellsthe limits of the earlier divisions can be plainly traced, and the spermato-cytes are in irregular blocks marking the early divisions. While withinthese blocks of cells the nuclei are usually in the same stage of mitosis,each segment of the antheridium may show a different stage of nucleardivision. This was also noted by Humphrey in his study of Fossombronialongiseta [1]. Spermatogenesis Pallavicinia Zollingeri proved the best species for a study of sperma-togenesis, and the investigation of this subject was mainly devoted to thatspecies. In the earliest stages procurable the final mito
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Keywords: ., bookauthorcampbelldouglashought, bookcentury1900, bookdecade1910
