BOTANY. 747 



carrots, red beets, sugar-beet roots, vetch, and cucurbit seedlings, leaves 

 of rhododendron, viburnum, and acacia, shoots of veronica and twigs 

 of SiiUx alba. The api)aratus principally used was the Pfefter-Petteu- 

 kofer respiration apparatus with a modified form of Stich's apparatus 

 for determining the equation between oxygen and carbon dioxid. The 

 injury was caused in various ways. Potatoes, carrots, etc., were cut in 

 fours, leaves Avere slit longitndinallj^ while with the seedlings the hyp- 

 ocotyl was split or the root tip was cut off. Immediately alter injury 

 the parts were washed and partly dried to remove all injured cells and 

 to secure turgidity, after which they were subjected to the conditions 

 of the experiment. The results obtained are tabulated and discussed 

 at considerable length. 

 The summarj^ of conclusions as stated by the author is as follows: 



"(1) Thiit after injury to plant tissue there results a greatly increased resiiiration, 

 varying iu intensity and duration with the character of the tissue involved and 

 with the extent of the wounding. This increased activity of respiration, after 

 reaching — usually within 2 days — a maximum, falls gradually, as the wounds heal 

 over, to a normal or to an almost normal rate. 



"(2) That this increased respiration may l)e ascribed to an ert'ort on the part of the 

 plant to recover from the injury by which the ordinary functions of the plant are 

 stimulated, thereby demanding and necessitating an increased supply of oxygen. 



"(3) That in large, bulky tissues there is in the natural condition a certain amount 

 of inclosed or absorbed carbon dioxid, some of which is given oft' very suddenly 

 during the first 2 or 3 hours after injury, thereby indicating a seemingly higher 

 respiratory activity than in the hours which immediately follow. 



"(4) That, in the plants experimented with, the ratio of the absorption of oxygen 

 and production of carbon dioxid does not vary within very wide limits before and 

 after injury, thougli there is a distinct, if small, increase in the proportion of carbon 

 dioxid given off in the latter case. Also, that the amount of oxygen absorbed is 

 always in excess of the amount theoretically required for the quantity of evolved 

 carbon dioxid.'' 



The influence of continued electric currents on the decompo- 

 sition of carbon dioxid in aquatic plants, M. Thouvenin {Rev. gen. 

 Bot., s {1S9(J), Xo. 95,2^P' 4S5-4'>0,figs. 9). — The author has investigated 

 the decomposition of carbon dioxid and liberation of oxygen as affected 

 by a weak continuous electric current. Aquatic plants were so placed 

 in water charged with carbon dioxid that a current of electricity could 

 be passed through them and the oxygen bubbles observed, collected, and 

 analyzed. The plants were placed in the sunlight so that the activity 

 of the chlorophyll would not be impaired. The plants experimented 

 with were Elodea canadensis, Myriopliyllum sjpicatum, and Potamogeton 

 pcr/oUatus. The number of bubbles of oxygen observed was very 

 appreciably increased when the plant Avas electrified, in some cases 

 they were given off' too rapidly to be counted. 



Two possible objections are raised to the results, namely, the current 

 may electrolyze the water, or it may decompose the carbon dioxid in it, 

 and in either case oxygon would be given off". These are met with the 

 statement that iu no case was tbe current sufficiently strong for the pur- 

 pose, 0.0035 amperes being the strongest employed, and when the plant 

 15502— No. 9 2 



