14 NATURAL SCIENCE [July 



Ox Willows 



The March number of the Botanical Gazette opens with a useful 

 paper by C. J. Chamberlain, entitled " Contribution to the life 

 history of Salix." The author has worked out the development of 

 the flower, and that of the microspores and macrospores, and their 

 germination, the process of fertilisation, and the embryology in 

 several species of willows growing in the northern United States. 



In view of the results of the work of Treub, Nawaschin, and 

 Miss Benson, on Casuarina and various genera of the so-called 

 Amentiferae, considerable interest attaches to Mr Chamberlain's 

 researches. 



He finds that Salix shows none of those striking divergences 

 from the usual course of events in the ovule, which have been 

 demonstrated in the above-mentioned genera, and his results con- 

 firm previous views as to the primitive simplicity of the willow 

 flower. A diligent search in buds, both of the male and female 

 flowers, failed to reveal the slightest trace of a rudimentary perianth, 

 such as might be expected were the floral simplicity the result of 

 reduction. The path of the pollen-tube is perfectly normal, an 

 entrance to the ovule being effected through the micropyle. The 

 synergids have a strongly developed beak, and breaking through 

 the embryo-sac, project into the micropyle and attract the 

 pollen-tube. 



Great difficulty was experienced in finding the antipodal cells 

 in the embryo-sac; only in six cases out of several hundreds examined 

 were they clearly seen. This leads the author to suggest that their 

 reputed absence in Casuarina may be due to a similar difficulty. 

 The course of cell-division, in the development of the embryo from 

 the fertilised ovum, shows several differences in detail from that 

 described by Hanstein for Cajjsella. 



Some interesting sports were also noted. Besides the well- 

 known mixed catkins, which were observed in considerable number 

 on a vigorous plant of S. glaucophylla in three successive seasons, 

 the writer describes and figures the growth of stamens inside the 

 ovary, an occurrence hitherto unknown in Salix. These intra- 

 ovarian stamens consisted generally of a one-celled stalked or sessile 

 anther, borne on the wall of the carpel or on a placenta-like out- 

 growth. Occasionally these ambisporangiate ovaries had a perfectly 

 natural appearance, but generally they were more or less deformed. 

 The ovules were generally inverted (anatropous), their normal form ; 

 but occasionally upright (orthotropous) ovules were found, sometimes 

 borne on a long stalk. Quite normal embryo-sacs and embryos were 

 produced in these sporting pistils. Masters in his "Teratology" 

 mentions only one authenticated case of the formation of stamens 



