164 Biologie. — Morphologie, Befruchtung, etc. 



not adaptatiuns to xerophytic conditions. . ., nor are they "inherited" 

 from the remote past as vestigial characters . . . , but are the result 

 of physiological limitations of the t>^pe of wood in this ancient and 

 incompletely evolved group. In other words their "xerophytism" is 

 not ecological, but phylogenetic." W. G. Smith (Leeds). 



Chamberlain, C. J., Preliminary note on Ceratosamia. (Botan. 

 Gazette XLIII. p. 137. Feb. 1907.) 



Ceratosamia is to be added to the list of cycads in which motile 

 spermatozoids have been observed. Material obtained from densely 

 shaded woods in Mexico showed the motile cells in the month of 

 June, hence fertilization takes place more than a year after poUina- 

 tion. "The ovulate cones disintegrate and free the seeds soon after 



fertilization The seed has no resting period, but growth is con- 



tinuous from fertilization to the leafy plant." M. A. Chrysler. 



Gates, Reginald R., Pollen Development in Hybrids of 

 Oenotheralatay^O. Lamarckiana, and its relation to Mutation. 

 (Botanical Gazette. Vol. XLIII. p. 81—115. Pls. 2-4. 1907.) 



Pollen development was studied in hybrids of Oenothera La- 

 marckiana c? X ^- ^^^^ ?> ^ mutant. This cross produces the two 

 parent types in the first hybrid generation. O. lata does not mature 

 its poUen and much of the paper is devoted to a description of 

 pollen degeneration in this mutant. The possible causes of sterility 

 in hybrids are also discussed. 



Contrary to Pohl's Statement, the tapetum does not grow into 

 the loculus and prevent the development of the pollen cells. After 

 the pollen and tapetum have degenerated at the end of the tetrad 

 divisions, the wall layers often grow in and fill the empty loculus. 

 In the tetrad divisions, which usually take place, small extra nuclei 

 are frequently found, formed by chromosomes left behind in the 

 cytoplasm. The occurrence of such extra nuclei in the pollen deve- 

 lopment of so many hybrids suggests the possibility that all plants 

 in which they occur, including the well known case of Hemerocallis 

 flava, may be hybrids. 



The first reduction mitosis in the pollen mother-cell of the O. 

 Lamarckiana hybrid is also described. In both plants ring-shaped 

 bodies are found on the spindle or in the cytoplasm, having other- 

 wise the appearance and size of chromosomes. In O. lata large rings 

 of chromatin were observed in the prophase after synapsis and it 

 is suggested that this may be the method of origin of the ring-shaped 

 bodies, which are called heterochromosomes. 



Apparently the most important point developed in the investi- 

 gation is that O. lata has 14 chromosomes as the sporophyte num- 

 ber, while the O. Lamarckiana hybrid has at least 20. It is concluded 

 that the mutants probably arise during the reduction mitosis and 

 that a cytological basis for mutation ma}'- be found. 



The seeds from which the plants were grown were obtained 

 from de Vries pure cultures. Charles J. Chamberlain (Chicago). 



Küster, E., Vermehrung und Sexualität bei den Pflanzen. 

 (Leipzig, B. G. Teubner. 1,25 M. 1906.) 



Da die botanische Lehrbuchliteratur kein Werk enthalt, das die 



