ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 463 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Cytology, 

 including: Cell-Contents. 



Karyokinesis in (Edogonium.*— C. van Wisselingh finds that the 

 karyokinesis in (Edogonium agrees closely with that of higher plants ; 

 the origin of the chromosomes, formation of the nuclear plate, etc., 

 resemble those of the embryo-sac of Fritillaria and Leucojum. The 

 nucleolus is like that of higher plants, but unlike that of Spirogyra. 

 There are nineteen chromosomes of very different lengths, some of 

 which are heterogeneous. The author considers that the production of 

 four swarm-spores upon germination of the oospore, is very significant, 

 and he regards CEdogonium as a generation with a simple number of 

 chromosomes, reduction taking place in the oospore. From this it 

 would follow that it exhibits no alternation of generations. 



Function of the Centrosome.f — R. F. Griggs has made a cytological 

 study of Synchytrium, with the ultimate hope of correlating it with 

 other plants and animals, in such a way as to throw some light on the 

 general problems of cell-organisation, and finally to arrive at some con- 

 clusions regarding the relationships of the Chytridiales. While the 

 exact history of the structures here described is provisional, the present 

 work confirms Kusano's statements that the rays of the centrosome 

 inclose the vacuole which surrounds the chromosomes, and form the 

 deeply staining nuclear membrane around it. 



Structure and Development. 

 "Vegetative. 



Historic Fossil Cycads.J — <>• R. Wieland gives a brief account of 

 Cycadeoidea etrusca, C. Reichenbachiana, Williamsonia gigas, and Anomo- 

 zamites minor. 



The vegetative features of G. etrusca agree closely with those of the 

 Maryland Cycads ; the synangia are clearly of the Marattiaceous type, 

 while the pollen is seemingly mature. G. Reichenbachiana has a columnar 

 type of trunk with very large leaf-bases, and its flower-buds agree closely 

 with those of G dacotensis ; the author considers that, in the light of 

 the new facts disclosed by this specimen, English writers are mistaken 

 in classing the Cycadeoidese in the Bennettitea?, and that the latter term 

 should be used in a very restricted sense. Williamsonia gigas forms an 



* Bot. Centralbl., xxiii. (1908) pp. 137-56 (1 pi.). 



t Ohio Nat., viii. (1908) pp. 277-86 (2 pis.). 



X Arner. Journ. Sci., xxv. (1908) pp. 93-101 (1 fig.). 



