666 SUMMARY OF CURRENT RESEARCHES RELATING TO 



destructive effect on bacteria, have no influence, one way or the other, on 

 the germinating power of the seeds of the higher plants, even after long 

 exposure. The experiments were made on Oryza sativa, Hclianthus 

 annum, Erodium cicutarium, Datura Stramonium, Allium fistulosum, 

 Erythraea centaurium, Nicotiana rustica, and Vicia Faba. 



Ripening of Shoots of the Vine.*— F. Kovessi gives further details 

 of his observations on various species of Vitis. He adopts as a general 

 statement the conclusion that ripening consists, from an anatomical 

 point of view, in a development and differentiation of the tissues of the 

 plant subsequent to the formation of the bark, a browning of the 

 cortex, development of the xylem and phloem rings, reduction of the 

 pith, thickening of the cell-walls, and increase in the amount of starch. 

 The proportion of water in the branches is also greatly reduced, 

 enabling them to resist a greater intensity of cold. The favourable 

 conditions for ripening are strong light, a high temperature, and a small 

 amount of moisture in the air. 



Parasitism of Buckleya.t — S. Kusano publishes an account of the 

 parasitism of Buckley a Quadriala, belonging to the Santalaceae. The 

 haustoria appear to attack the roots of almost any plant. As a result 

 of the attack the activity of the cambium of the host-root seems to be 

 much increased. The same organ of the parasite can apparently main- 

 tain its activity during fifteen years, and probably longer. 



Periodicity in the Growth of the Root. $ — J. Hammerle has in- 

 vestigated the phenomena connected with the periodicity in the formation 

 of roots, especially in the sycamore (Acer pseudo-platanus). He finds 

 there are two annual periods of growth when the root increases in 

 length and produces new lateral roots, viz. in the spring and the 

 autumn. From January to March is a period of entire rest. Similar 

 results were obtained with Quercus, Salix, and Corylus, but not with 

 Fagus. 



Periodic Growth in the Potato. § — Prof. C. MacMillan states that 

 there is a rhythmic increase of growth in the potato-tuber, with maxima 

 once or twice, or oftener, in 24 hours, followed by minima, when growth 

 nearly or quite ceases. 



Movement of Water in Plants.||— K. Fuchs gives further evidence 

 in favour of the already accepted theory that a cell the active contents 

 of which are not homogeneous must absorb water from one side and give 

 it out on the other, in other words must act as a pump ; thus confirming 

 the theory already enunciated by Pfeffer. 



Transpiration and the Resistance of Stems. 1" — A series of experi- 

 ments by C. C. Curtis lead him to the following general conclusions. 

 By means of pressure tests a definite measure of the resistance of a 

 given length of stem to the transpiration current may be obtained, and 



* Eev. Gen. de Bot. (Bonnier), xiii. (1901) pp. 193-211, 251-64, 307-25 (7 pis. 

 and 3 fie-s.). Cf. this Journal, ante, p. 302. .,,„„,„, , ,« 



t Bolt Mag Tokyo, xv. (1901) pp. 42-6. See Bot. Gazette, xxxi. (1901) p. 440. 



1 Beitr z wiss. Bot. (Fiinfstuck), iv. Abt. 2. See Bot. Ztg., lix. (1901) p. 230. 



S Bull Minn. Acad. Nat. Sci., iii. (1901) pp. 355-62. See Bot. Gazette, xxxi. 

 (1901) p. 439. || Beih. z. Bot. Centralbl., x. (1901) pp. 305-8 (3 figs.). 



f Bull. Torrey Bot. Club, xxviii. (1901) pp. 335-48. 



