ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 193 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including - Cell-Contents. 



Spindle Formation in the Pollen-Mother-Cells of Cassia tomen- 

 tosa.* — H. T. A. Hus finds that the cytoplasm of the young pollen- 

 mother-cells consists of a network of radially arranged fibres, on and 

 between which large and small granules are formed. The meshes next 

 the nuclear wall are smaller and elongated, parallel to the wall. A 

 granular zone appears around the nucleus, and at the same time deeply 

 staining rough fibres, often arranged in conical groups, appear in the 

 cytoplasm. In the next stage a felt-like zone more or less completely 

 surrounds the nucleus, and the deeply staining fibres of the cytoplasm, 

 now united into cones, establish a connection with the fibres of this zone. 

 The linin threads become parallel with the other fibres and also with the 

 axis of the larger cone. As soon as the rough threads of the fibres 

 become smooth the nucleolar wall breaks down, the linin and the kino- 

 plasmic fibres anastomose and become grouped in bundles. A multipolar 

 spindle is formed, two cones of which, opposite to each other, are more 

 prominent, and gradually absorb the smaller cones. The spindle of the 

 second division is more markedly multipolar than that of the first 

 division. The author concludes that the spindle formation in this species 

 forms a connecting link between the multipolar polyarchal spindle anlage 

 usually met with in dividing mother-cells of pollen, spore and embryo- 

 sac and the multipolar diarchal spindle anlage of vegetative cells. 



Structure of the Starch-Grain.t — R. H. Denniston finds in de- 

 veloping starch-grains of various sorts an outer sharply defined layer 

 next the plastid, which takes up orange strongly from the safranin- 

 gentian-violet-orange stain, the body of the grain becoming bright violet. 

 After partial digestion by diastase the grains show the orange-staining 

 layer little affected, while the violet part is much dissolved, and orange- 

 staining material appears in the corroded interior. The author suggests 

 that the outer layer is different from the rest, and believes it to be a 

 carbohydrate not yet fully polymerised to starch. 



Structure and Development. 

 Vegetative. 



Regeneration in Zamia.} — J. M. Coulter and M. A. Chrysler give 

 some account of the remarkable power shown by mutilated stems of 



* Proc. Calif. Acad. Sci., iii. pt. 2 (1904) pp. 329-54 (3 ph.). See also W. J. Land 

 in Bot. Gazette, xxxix. (1905) p. 74. 



t Trans. Wis. Acad., xiv. (1904) pp. 527-33. See also Bot. Gazettp, xxxviii. 

 (1904) p. 47::. X liot. Gazette, xxxviii. (19u4) pp. 452-X. 



