ZOOLOGY AND BOTANY, MIOKOSCOPY, ETC. 769 



the part played by the secondary wood in the conduction of sap, and the 

 importance of the anastomosing of the veins in the leaves for the supply 

 of water to the transpiring surfaces. 



In all the trees examined, with possibly the exception of the horse- 

 chestnut, only a portion of the alburnum of the branches has the power 

 of conduction, and even this portion displays the property in very 

 different degrees, the last annual ring exhibiting it the most strongly. 

 The method of examination was by causing the wood to absorb a soluble 

 pigment, and the same results were obtained with fuchsin and with 

 methylene-blue. The different vessels in the same vascular bundle 

 display very different properties in this respect. The author confirms 

 Pfeffer's statement that many soluble aniline-pigments pass readily 

 through the protoplasm. 



Development of Wheat.* — M. Balland states that an ear of corn 

 rapidly increases in weight and attains its maximum about the thirtieth 

 day after flowering ; it then diminishes progressively during the fifteen 

 days which precede harvest. The grain follows the same course, but it 

 attains its maximum a few days later. Inversely the other parts of the 

 ear (the rachis and chaff) diminish up to the moment when the grain 

 attains its maximum ; they are then to the grains nearly in the pro- 

 portion of one to four. While the grain grows, the acidity of the nutrient 

 fluids diminishes, and we are able to follow the condensation of the 

 soluble alluminoid matter simultaneously with the transformation of the 

 sugar into starch. 



Root-pressure. "f — Mr. C. B. Clarke represents the accepted doctrine 

 regarding root-pressure thus : — ^" Another kind of motion of water in the 

 plant, depending not on suction but on pressure from below, is caused by 

 the roots. It is the root-pressure which forces out drops at particular 

 points of the leaves." The author denies that root-pressure exists in 

 any case, and maintains that the whole mechanical fluid action in plants 

 must be considered in accordance with the laws of capillarity. 



Curvature of Plants. | — M. F. Elving states that it is well known 

 that plants grow in a certain direction, and that this direction is deter- 

 mined by their weight, by radiation, humidity, &c., and that they seek 

 to regain their normal position by characteristic curvatures if they are 

 in any way disturbed. If a tube containing Phycomyces nitens is placed 

 horizontally, the first effect noticeable is a movement of the protoplasm 

 towards the uppermost wall of the cell ; in consequence of this, growth 

 takes place to a greater extent in the upper part. It may be taken as a 

 general rule, then, that flexion of a stem favours the development of the 

 coUenchyma on the convex side, while hindering it on the other side. 



Influence of certain Rays of the Solar Spectrum on Root-absorp- 

 tion and on the Growth of Plants.§ — Mr. A. B. Griffiths and Mrs. 

 Griffiths daily exposed mustard and bean plants grown in calcareous soil, 

 to which had been added a definite amount of ferrous sulphate, to various 

 portions of the solar spectrum. Incineration of the plants showed that 

 the greatest amount of ferric oxide was contained in those exposed to the 



* Comptes Eendus, cvi. (1888) pp. 1610-2. 

 t Journ. of Bot, sxvi. (1888) pp. 201-3. 

 X Morot's Journ. de Bot., ii. (1888) pp. 197-200. 

 § Proc. Eoy. Soc. Edin., cxxiii. (1887) pp. 125-9. 



