ZOOLOGY AND BOTANY, MICROSCOPY, ETC. L83 



remarkable in this instance are the extent and duration of this cam- 

 bium. Aechmea Pineliana exhibits certain colour-reactions, showing 

 that the cells contain some unknown chemical compounds in theii 

 parenchyma-cells. 



Reproductive. 



Flower-morphology and Embryology of Datisca.* — W. Himmel- 

 baur has studied Datisca cannabina and finds that the whole inflores- 

 cence is a thyrsus ; the individual parts of it, however, are more or less 

 complete dichasia. The female flower has three inferior carpels and 

 three superior perianth-leaves. The placenta tion is marginal-parietal. 

 The seed usually contains one embryo-sac mother-cell, which divides 

 ouce and then develops into the embryo-sac. The archegonium com- 

 pletely disappears from the embryo-sac. The flower must be fertilised 

 and the pollen-tube pushes its way by the funicle through the micropyle 

 to the egg-apparatus. The opinions enunciated concerning partheno- 

 genesis in this plant appear to be due to misconception. 



Embryology of Penseaceas.f — E. L. Stephens has examined five species 

 belonging to the genera Sarcocolla, Pensea and Brachysiphon, and records 

 several interesting facts in connection with their embryology. The embryo- 

 sac mother-cell arises in the sub-dermatogen layer, and when heterotypic 

 division occurs it already consists of four to five cell-layers. It develops 

 directly into the embryo-sac. A central vacuole gradually forms, and 

 here the four nuclei collect. By division sixteen nuclei are formed which 

 arrange themselves symmetrically in four groups, which give rise to four 

 groups of cells. Three of these groups unite and ultimately give rise to 

 the egg-apparatus and the antipodal cells. The four free nuclei remain 

 in the centre of the cell, and later on unite with the second nucleus of the 

 pollen-tube to form the secondary nucleus of the embryo-sac. Endo- 

 sperm-formation starts directly the embryo begins to develop. Usually 

 embryo-development begins in the upper cell-groups, but development 

 from lateral cells has also been seen. Polyembryony has been observed, 

 but no instance of parthenogenesis or apogamy. 



Physiology. 

 Nutrition and Growth. 



Utricularia. — P. von Luetzelburg has studied many species of 

 Utricidaria, and concludes that they are truly insectivorous, being able 

 to digest the insects which they catch owing to the secretion of an 

 enzyme and an acid. The hairs which entrap the insects secrete sugar 

 and mucus, but have no digestive action. The bladders are all of 

 similar structure, and the flap closes so tightly owing to the mucus 

 present that no insects can possibly get out. The direction of growth 

 is strongly influenced by heliotropism and geotropism. Winter-buds 

 can be produced artificially at any time. By special culture, also, the 

 inflorescence axis can be made to produce lateral branches and growing 



* SB. Akad. Wiss. Wien, cxviii. (1908) pp. 91-113 (1 pi. and 4 figs.), 

 t Ann. Bot., xxiii. (1909) pp. 363-378 (2 pis.). 

 X Flora, c. (1909) pp. 145-212 (48 figs.). 



