ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 69" 



(2) Nutrition and Growth, (including: Germination, 

 and Movements of Fluids). 



Chlorophyll Assimilation.* — Sig. G. Pollacci lias confirmed, by a 

 fresh series of observations, his previous statement that green leaves 

 ■still in connection with the plant exhibit Schiff's aldehyd reaction ; 

 while this is not the case with leaves which have been darkened for 

 some days, nor with plants grown in an atmosphere devoid of CO.,, 

 nor with fungi. A great variety of reactions agree with the deter- 

 mination of this aldehyd as exclusively formic. He promises further 

 experiments for the purpose of isolating the aldehyd. 



Effect of increased Pressure on Chlorophyll Assimilation.f — Ex- 

 periments made on several different plants have led M. J. Friedel to 

 the conclusion that a lowering of the pressure even as low as to one- 

 fourth of the normal does not alter the nature of the chlorophyll 



. CO., . . 



assimilation, the value of the proportion ..- remaining nearly at 



unity ; while the intensity of the assimilation diminishes with the de- 

 crease of the pressure, following a nearly regular law. 



Influence of Dry and Moist Air on Plants.} — As the result of a 

 series of experiments on a considerable number of plants belonging to 

 many natural orders, M. Eberhardt lays down the general law that 

 moist air promotes the development of both stem and leaves, but re- 

 duces the diameter of the stem ; has a tendency to increase the surface 

 of the leaves ; diminishes the quantity of chlorophyll contained in 

 them ; and greatly reduces the production of rootlets. Dry air, on the 

 other hand, has an unfavourable effect on the growth of the stem ; 

 has a tendency to diminish the surface of the leaves ; and increases 

 the number of rootlets. As regards the tissues : — dry air increases 

 the thickness of the cuticle and the number of stomates ; promotes the 

 formation of hark ; favours the production of woody tissue and the 

 differentiation of the sclerenchymatous tissues, both in the pith and 

 in the cortex ; and increases the development of the palisade-tissue in 

 the leaf. In moist air, on the contrary, the differentiation is less than 

 under normal conditions, especially in relation to the supporting tissue. 



Limits of Grafting.§ — M. L. Daniel finds the grafting by approach 

 of two species to be possible within much wider limits than has hitherto 

 been supposed. He has succeeded in inducing union in the case of young 

 seedlings, between members of the following widely separated genera : — 

 Phaseolus and Xanthium, Phaseolus and Bicinus, Helianthus and Cucur- 

 bita, Brassica and Lycopersicon, Chrysanthemum and Lycopersicon, Heli- 

 anthus and Solanum, Coleus and Achyranthcs, Cineraria and Lycopersicon^ 

 Aster and Phlox, Coleus and Lycopersicon, Acer and Syringa, Zinnia and 

 Lycopersicon. In all these cases there was a complete and permanent 

 union ; those grafts were always the most perfect in which there was 

 the greatest resemblance between the two species in size, vigour, and 

 mode of growth. 



* Atti K. 1st. Pot. Univ. Pavia, vii. (1899) 2] pp. See Bot. Ztg., lviii. (1900) 

 2 te Abt., p. 154. 



t Comptes Eendus, exxxi. (1900) pp. 477-9. 



X Tom. cit., pp. 193-G, 51o-5. § Tom. cit,. pp. 192-3. 



