766 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Underground Germination of Isopyrum thalictroides.* — This 

 species presents one of the few examples of underground germination 

 among flowering plants. A. Winkler has examined the process in its 

 various stages, and points out that it exhibits a difference from the 

 similar phenomenon in Anemone nemorosa and ranunculoides belong- 

 ing to the same natural order. While in Anemone the unstalked 

 cotyledons project from the testa of the seed, and, as in typical 

 dicotyledons germinating above the surface of the soil, are opposite to 

 one another, in Isopyrum they remain inclosed within the testa, and 

 are placed on tolerably long stalks. 



Stomata of Pandanaeese.t — R- F. Sella has closely studied the 

 stomata in the leaves of a large number of species of Pandanus, and 

 distinguishes three types : — (1) the simplest and most common form, 

 represented by Pandanus inermis, in which the cells contributing to 

 its formation are only two in number ; (2) the type of P. graminifolius, 

 which occurs only in a few Pandanacese ; the auxiliary cells, eight in 

 number, are all thickened, their apices thus forming a protuberance 

 which rises above the level of the epidermal cells, the walls of the 

 latter being also thickened ; (3) the type of P. utilis, resembling the 

 stomata of Aloe and other allied plants ; the thickening here extends 

 from the auxiliary cells to the epidermal cells to such an extent as to 

 form little lumps on the surface, completely concealing the outline 

 of the stoma. A number of measurements are given of the size of 

 the stomata in different species, and of the relative number found on 

 a unit of superficies. 



Changes in the Gland-cells of Diongea muscipula during 

 Secretion.* — According to W. Gardiner there are four periods in tho 

 process of digestion by the leaves of the Venus's fly-trap, viz. the 

 resting, the secreting, the absorbing, and the period of recovery. 



In the resting stage the gland-cells exhibit the following structure : 

 — In each cell the protoplasm is closely applied to the cell-wall, 

 leaving a large central vacuole, which is filled with the usual pink 

 cell-sap. The protoplasm is very granular, especially round the 

 nucleus, which is situated at the base of the cell, and is large and 

 well defined. At the end of the secreting period, which appears to 

 be about twenty -four hours after stimulation, movements of the pro- 

 toplasm have taken place, in consequence of which the nucleus now 

 occupies the centre of the cell ; numerous strands of protoplasm 

 radiate from the nucleus to the parietal protoplasm, dividing the 

 vacuole into several smaller ones. The protoplasm is now nearly 

 homogeneous, clear and hyaline, and the nucleus has become much 

 smaller. In the ordinary leaf-tissue special cell-contents make their 

 appearance after the absorption of the food. About thirty-six hours 

 after feeding the cells contain a large number of tufts of crystals in 

 the vacuole, which adhere to the inner surface of the protoplasm. 

 They consist of fine acicular crystals, which crystallize out with 

 great regularity, and radiate from a central point. They are of a 



* Flora, Ixvii. (1884) pp. 195-8 (1 pi.). 



t Nuov. Giorn. Bot. Ital., xvl (1884) pp. 171-82 (2 pis.). 



X Proc. Roy. Soc, xxxvi. (1884) pp. 180-1. 



