666 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



In the second communication Heir Lindemuth gives a further list of 

 37 species, whose leaves he has found capable of producing roots, and 

 some of them have already given rise to buds and shoots. 



Much remains to be discovered in regard to the dependence of the 

 process on the age of the leaf, its position on the stem from which it is 

 derived, and the time of year. In some cases the author found that 

 leaves could root readily at one time and not at another a few weeks later. 

 Frequently roots only can be produced without signs of bud formation, 

 and the bud produced may be either a flower-bud or a leaf-bud, according 

 to the position the leaf occupies on the plant from which it is taken. 



J. P. 



Leaf-spots on Linden and Elm Trees {U.S.A. Exp. Stn. Hatch, 

 JIass., Ann. Rep. 1903, p. 35). — These fungi seem to thrive chiefly upon 

 older trees and trees in poor condition. This is particularly noticeable 

 with the leaf-spot which attacks Lindens (Cercospora micros or a), and this 

 fungus is worse in its effects than the Elm leaf -spot (Dotliidella ulmea). 

 Spraying is recommended twice in the summer, and it is estimated that 

 sprayed trees gain two to five per cent, in growth and development. The 

 leaves will also remain green longer, and not drop so soon as on unsprayed 

 trees.— V. J. M. 



Leaves with the Function of Support. By F. W. Neger (Flora, 

 vol. xcii., 1903, pp. 380-395 ; 2 cuts).— The down-turned lower leaves of 

 Geranium Robcrtianum help its support when growing on a vertical 

 surface ; after the blade fades the petiole long remains fresh and acts as a 

 stay. On removing these so that the stem bent down, after two or three 

 days, the leaves at the next node curved down as supports, while the stem 

 above turned up at a right angle. Thus the mechanism is one of corre- 

 lation in relation to " morphassthesia." Leaves of similar function occur 

 in G. Incidnm and Stellaria nemorum. — M. H. 



Leguminosae Tubercles. By R. Stormer (Nat. Zeit. Land-Forst. 

 i. pp. 130-146, with 3 figs.; 1903). — A review, by an active investigator, 

 on our present knowledge regarding the root- tubercles of Leguminosce. A 

 brief summary of earlier work leads up to the subject of "Nitragin," those 

 pure cultures of the bacterial organisms, which a few years ago were so 

 much spoken about. Up to the present " Nitragin " has not fulfilled all 

 that was expected of it in improving the yield of leguminous crops. The 

 main part of this paper is a review of the causes of failure, and of recent 

 investigations on how this is to be prevented. Two things of prime im- 

 portance are the strength or virulence of the tubercle-organisms, and the 

 method of infecting crops with the pure cultures. If the organism is too 

 virulent the leguminous host suffers ; if not virulent enough, then the 

 host-plant dominates. In either case the tubercles are not fully developed, 

 and the crop does not benefit. A good deal has been learnt recently about 

 the degree of virulence needed to secure infection. " Nitragin " failures 

 were chiefly due to the method of application (viz. either mixed with 

 Water and sprayed on to the land, or mixed with earth and strewn on the 

 surface). The result was that the organisms failed to reach the roots of 

 the crop. Recent experiments in infecting the seed before sowing have 



