434 Morphologie, Teratologie, Befruchtung, Cytologie. 



Ishikavira, M., Ueber die Zahl der Chromosomen von 

 Gi72kgo biloba. (Bot. Mag. Tokyo. XXIV. 285. p. 225—226. 2 Textfig. 

 1910.) 



Die Angaben verschiedener Forscher über die Chromosomen- 

 zahl bei Ginkgo biloba stimmen nicht 4iberein. Bald hat man 12, 

 bald 7 oder 7 — 10 bei der Pollen- oder Embryosackbildung angege- 

 ben. Nach Verf. beträgt die Zahl der Gemini oder Chromosomen 

 bei der hetero- und homöotypischen Kernteilung in der Pollenmut- 

 terzelle immer 12. Unter diesen 12 Gemini ist eins durch seine 

 Grösse ausgezeichnet. S. Ikeno. 



Kuwada, Y., A Cytological Study of Orisa sativa L. (Bot. 

 Mag. Tok5ro. XXIV. 287. p. 267—281. 1 PI. 2 Textfig. 1910.) 



During the development of pollen-grains of Orisa sativa, we 

 see throughout the prophase of the heterotypic division the parallel 

 arrangement (not end-to-end) of chromatin threads, which soon 

 change into 12 gemini. In the homotypic division, it is very re- 

 markable that some chromosomes are arranged in pairs ("pseudo- 

 gemini") group of more than two. 



The embryo-sac formation is normal. The antipodals divide 

 repeatedly as in other Gramineae. The author did not observe the 

 double fertilisation itself, but thinks that it really takes place. In 

 the endosperm-formation the vvrall-formation is offen suppressed and 

 the daughter-nuclei come to fusion. S. Ikeno. 



Saxton, W. T., Contributions to the Life Histor^^ of 

 Widdringtonia cupressoides. (Bot. Gaz. L. p. 31 — 48. P). 1 — 3. 1910.) 



About 64 megaspore mother cells are organized but only one 

 functions. A large number of archegonia, 30 to about 100, are 

 arranged in several groups, but never at the apex of the prothallus. 

 Pollination occurs in January and fertilization about 15 months later, 

 the development being continuous with no break such as occurs in 

 temperate conifers. The development of the male gametoph3'te is 

 about as in other members of the Cupressineae. In the development 

 of the proembryo, walls are formed when less than eight free nuclei 

 are present and the proembryo fills the entire egg. 



A paper on Callitris is in preparation and in this the two 

 genera, Widdringtonia and Callitris will be compared. 



Charles J. Chamberlain (Chicago). 



Smith, F. G., Development of the Ovulate Strobilus and 

 young Ovule of Zaniia floridana. (Bot. Gaz. L. p. 128 — 141. 

 22 textfig. 1910.) 



Stages are described from the appearance of sporophylls upon 

 the strobilus up to a rather late free nuclear stage of the endosperm. 

 The very young staminate and ovulate strobili can be distinguished 

 b}^ the difference in breadth, number of sporophylls and number 

 of meristematic points. A Single archesporial cell gives rise to a 

 group of cells, one of which becomes the megaspore mother cell, 

 and this gives rise to four megaspores. The spong}^ tissue is active 

 and nutritive during the earl}"^ stages of the embryosac; when it 

 begins to degenerate, the cells nearest the embryo-sac are first to 

 disorganize. Charles J. Chamberlain (Chicago). 



