ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 5 ( J 



in the anther-wall are mostly large, thin-walled, and contain hut little 

 protoplasm : hut, at the upper part of the anther, hoth the epidermal and 

 the hypoderinal layer of cells are very small and contain abundant pro- 

 toplasm with a large nucleus. The pollen-grains germinate while still 

 within the anther, and the pollen-tubes creep along the inside of the 

 anther-wall until they reach the small cells at the upper part of the 

 anther. These act in a manner comparahle to the conducting tissue of 

 the style and stigma ; their abundant food-material attracts the pollen- 

 tubes, which penetrate the wall of the anther at this point, and thus 

 reach the stigma which is exactly on a level with this portion of the 

 anther. 



Similar phenomena are presented by Viola canina and other species 

 of the genus. In Oxalis Acetosella the conducting tissue of the anther 

 extends along the whole length of the pollen-sacs on the side facing the 

 stigma. In Linaria spuria the cleistogamous flowers are not so sharply 

 differentiated, passing by insensible gradations into those of normal 

 structure. The pollen-grains do not germinate while still within the 

 pollen-sacs. The self-pollinated flowers of Leersia oryzoides are not 

 properly cleistogamous. 



Hybridisation of Hepatica.* — Prof. F. Hildebrand has tried a num- 

 ber of experiments on the hybridisation of three common species of 

 Hepatica, — H. triloba with blue and white flowers, H. angulosa blue, and 

 H. acutiloba white, and finds different results in different cases. All 

 the species are proterogynous. The crossing of R. triloba ? by H. angu- 

 losa £ produced flowers which surpassed either of the parents in beauty. 

 Crossing these two species in the other direction resulted in almost 

 entire failure with white H. triloba, while with the ordinary blue variety 

 of this species much better results were obtained. Hybrids between 

 H. acutiloba £ and H. triloba $ gave the singular result that the leaves 

 presented a close resemblance to those of one parent, while the flowers 

 were altogether those of the other parent. 



(2) Nutiitionl and! Growth, (including- Germination, 

 and^Movements of Fluids). 



Electrical Effect of Light upon Green Leaves.-j-— Dr. A. D. Waller 



has made a series of observations on this subject, using chiefly the leaves 

 of Iris. He concludes that the leaves of certain plants, under favourable 

 conditions of life, exhibit electromotive effects and after-effects amount- 

 ing to • 02 volt, positive or negative, in response to illumination. As 

 in the case of animal tissue, it is possible that the negative (inactive; 

 effect may be significative of dissimilation, and the opposite effect or 

 after-effect significative of assimilation. The absence of direct result 

 in petals indicates that chloroplasts are essential to the reaction. 



Influence of the Water of the Soil on the Development of 

 Plants4 — In the two instances investigated (oat and summer wheat) 

 — v. Seelhorst finds that the number of internodes in the haulm is 

 mainly determined by the turgor during the first period of vegetation, 



* Bot. Centralbl., lxxxiv. (1900) pp. 65-73. 

 + Proc. Eoy. Soc., lxvi. (1000) pi). 129-37 (5 figs.). 



X Journ. f. Landwirthsch., xlviii. Hett 2. p. 103. See Bot. Centralbl., lxxxiv. 

 (1900) p. 54. 



