NOTES ON RECENT RESEARCH. 



685 



full of interest. All these Seychelles plants possess an epidermis with 

 thick and generally smooth outer walls to the cells. The trees have 

 generally small, thick-walled epidermis cells. Almost all the others 

 (undergrowth, epiphytes, and ground plants) have large, thin -walled 

 epidermis cells. Thus the trees may be regarded as protected against 

 the mechanical effect of the wind by the smallness of the cells and thick- 

 walled character of the epidermis. The plants growing within the woods 

 fall into two groups. All those which form the undergrowth are not 

 protected against too great transpiration, because either the soil is wet 

 or the air is saturated with moisture. But all those which are epiphytes 

 have very few stomata and possess water-storage tissues. Only these 

 latter are xerophilous, all the others being, as regards number of stomata, 

 adapted to moist conditions. There is a special anatomical examination 

 of each of the twenty-five species under consideration. — G. F. S.-E. 



Effect of Copper Fungicides. 



Copper on Leaves, The Action of. By S.M. Bain (U.S.A. Exp. 

 Stn. Tennessee, Bull. vol. xv., No. 2; Ap. 1902, pp. 1-108 ; pis. i.-viii.). — 

 The investigations recorded in the chapters of this work are the outcome 

 of some preliminary experiments made at the Tennessee Experiment 

 Station in the year 1895 with a view to gaining some knowledge as to the 

 effect of fungicides on Peach foliage, which might be of some economic 

 value in the treatment of the disease commonly known as the Brown Rot. 

 The lines upon which the work was carried out are suggested in the table 

 of contents. " The rational method of procedure was, in the first place, 

 to select for a comparative study with the Peach plant several others whose 

 foliage is not susceptible to injury by fungicides. For this purpose the 

 Grape and Apple seemed best fitted, for various reasons. . . . 



" By a comparison of these plants from various physiological and histo- 

 logical points of view, it was hoped to gain some information that would 

 lead to some practical beneficial result, or at least to a clearer under- 

 standing of the real problem underlying the whole investigation. Why is 

 the foliage of the Peach more susceptible to injury by fungicides than that 

 of other plants ? " The answer to this is given in the summary as 

 follows : — 



" Peach foliage is very susceptible to injury by fungicides because : 



" (1) Peach leaves (not the whole plant) are especially sensitive to 

 poisons in general, and to copper in particular. 



" (2) They have the power, which may or may not be possessed by the 

 leaves of other plants, of dissolving copper hydroxide. 



" (3) They have a cuticle which is thinner and more permeable than 

 that of some other leaves. 



** (4) They have glandular surfaces terminating their marginal teeth, 

 which are especially fitted, by reason of their thin cuticular covering, for 

 the absorption of copper in solution. 



" (5) They are especially sensitive to the various agencies prodtccing 

 leaf-fall by a normal absciss layer. 



" (6) They have the power, in common with other leaves of the genus. 

 Prunus, in a similar manner to exfoliate any injured region, this cx folia. 



