ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 485 



In the weaker solutions the roots endeavoured to rise out of the solution, 

 but as the solutions were made stronger the roots appeared to adapt 

 themselves and to plunge more deeply even than when in pure water. 

 Internal modifications in structure, e.g. absence of pith and abnormal 

 development of xylem, etc., correspond to external modifications. 



General. 



Traumatism in Relation to New Plant-forms.* — P. Becquerel 



contributes a note dealing with his work on Zinnia eleyans. The author 

 found that under the action of traumatism the floral structures under- 

 went certain sudden modifications, e.g. in the structure of the capitula, 

 change in colour of individual florets, and grouping of the flowers around 

 the branches. In order to avoid errors due to insect-pollination, certain 

 flowers were artificially pollinated and kept in muslin bags, and seeds 

 thus produced were used for experiments. The only characters trans- 

 mitted were those affecting the colour of the ligulate florets and of the 

 bracts of hermaphrodite flowers ; the author believes that the characters 

 thus brought out in plants which, like Zinnia, are polyhybrids, are atavic 

 or teratologic ones, which these genera have exhibited sporadically for 

 thousands of years. 



Remarks on Strephonema.f — M. Dubard has examined several 

 specimens of Strephonema Hook, fil., and is of the opinion that its cha- 

 racters are sufficiently distinct and marked to justify the formation of a 

 new family which would form a link with the Rosacea? (through the 

 Arnygdaleas) on the one hand, and the Combretaceas (through Ter- 

 jinnalia) on the other. The special characters of this family would be 

 the adherent base of the ovary, the semianatropic ovules, the peculiar 

 structure of the seed and embryo. 



Premature Fall of the Perianth. J — H. Fitting describes a series of 

 experiments made with the object of discovering the cause of the pre- 

 mature fall of the calyx and corolla. Most of the work was done in 

 connexion with Geranium pyrenaicum, but other species of Geranium and 

 plants like Erodium, Linum, Verbascum, Veronica, etc., which behave in a 

 similar way, were also used. The causes of the phenomenon are many and 

 various, and often act in a very short time. Usually the older flowers 

 are more easily affected than the younger ones. Chemical compounds 

 exert a striking influence. Thus the presence of coal-gas, excess of CO,, 

 tobacco-smoke, hydrochloric-acid vapour, chloroform, or ether vapour 

 causes a more or less rapid fall of the sepals and petals. In Verbascum 

 thapsiforme the results are seen in 30 seconds. Thermal variations pro- 

 duce similar results. In Geranium pyrenaicum response occurs at 40° C. at 

 the end of 2h minutes in old flowers, and 6 to 10 minutes in young ones ; 

 Linum, Verbascum, Borayo, etc., respond in 25 to 60 seconds, while some 

 species of Erodium respond at 33 o ~40° C. Shock, pollination, and 

 wounding of the pistil produce similar results. That the premature fall 

 is a vital process is evident, since it does not occur when the living 



* Comptes Rendus. clii. (1911) pp. 1319-22. 



t Rev. Gen. Bot., xxiii. (1911) pp. 220-3. 



\ Jahrb. wiss. Bot., xlix. (1911) pp. 187-2G6 (3 figs.). 



