452 EXPERIMENT STATION RECORD. 



the epidermis of the leaves, stating that wherever the copper penetrates the cuticle 

 ii acts injuriously upon the protoplasm of the leaf cells. The copper left in the soil 

 as a result of repeated sprayings can not be other than injurious to the plant, especially 

 if present in appreciable quantity. 



, The beneficial action of this fungicide is attributed to a number of factors, the 

 principal of which are the action of the lime, the repression of many insects by 

 spraying, and the influence of a thin coating of copper on the assimilation and trans- 

 piration < »f the plant. The latter of these factors is believed to be the most important , 

 and to it much space is given. The author considers that the thin coating of copper 

 hydrate on the leaves protects the chlorophyll against the injurious action of too 

 intense light and diminishes the transpiration of the leaves. No chemical action 

 takes place, the beneficial results being due solely to the physical action of the thin 

 layer of copper in reducing the intensity of light, As a practical application of this 

 theory, it is suggested that the strength of Bordeaux mixture might be regulated to 

 suit the character of the season, exposure, etc. 



Attention is called to the occasional injury to foliage and fruit from the use of 

 Bordeaux mixture. This seems due in many instances to the use of too little lime 

 in making the fungicide, but similar results have been observed when there was an 

 excess of lime used. The amount of injury seems to vary for different plants, and it 

 is influenced by different climatic conditions. In general the excess of lime seems 

 to check the injurious effects of copper sulphate, but in the case of apples and peaches 

 it is not wholly aide to prevent it, and in addition a superabundance of lime very 

 greatly reduces the adhesiveness of the fungicide. The excess of lime is also asso- 

 ciated with a reduction in the amount of copper hydrate, and, as a consequence, its 

 fungicidal action is diminished. 



The author inclines to the belief that in practice it will be found best to use equal 

 weights of lime and copper sulphate. There appears to be no reason for not following 

 this proportion in spraying grapes, apples, pears, and potatoes. For spraying 

 peaches 2 parts of lime to 1 part of copper sulphate should be employed, and the 

 number of applications should be as limited as possible, sprayings never being made 

 during rainy or cloudy weather. 



Notes on water transfer in plants, II. II. Dixon (Set. Proc. Roy. Dub/in Soc, 

 v. ser., 11 (1905), No. .', />/>. 1-12). — In considering the possibility of the participa- 

 tion of living cells of the stem of a plant in the elevation of the transpiration current, 

 the author has reviewed the experiments of Ursprung, who concluded that the cells 

 assist by directly elevating the water or partially supporting a hydrostatic head, and 

 by keeping the vessels and tracheids in a condition suitable for transmitting water. 

 The author carried on experiments with living stems and attached leaves, and he 

 gives quite a different interpretation of the results obtained. 



When portions of the stem w r ere killed by heat the leaves beyond wilted, indicat- 

 ing that the cells of the stem exercised no especial function in the elevation of water. 

 Where only very short portions of the stem were killed little injury appeared, but 

 when 2 to 5 cm. of the stem was killed the leaves showed injury in proportion to the 

 length of stem destroyed. This injury had a progressive effect, which is attributed 

 to the introduction into the leaves of poisonous or plasmolyzing substances from the 

 dead cells. This action was repeatedly shown by immersing freshly cut stems in 

 decoctions made by boiling stems of the same kind and cooling the fluid. As com- 

 pared with stems immersed in fresh water, wilting took place much earlier with 

 those immersed in the decoctions. 



In order to show that this effect was not due to clogging, the bottom of the 

 immersed stems was cut off at frequent intervals, and the injurious properties of the 

 decoctions were retained after repeated filterings. . Some slight injury may have 

 been due to clogging of the water-conducting tissues of the plant by comparatively 

 mpermeable substances, but the filtering would have removed most of these. 1 1 is 



