NOTES AND ABSTRACTS. 



Ill 



Disease-receptivity and Immunity. By E. Munch (Nat. 

 Zeit. Land-Forst), Vol. 7, pp. 54-75, 87-114, and 129-160, 8 figures, 

 January, February, March 1909). — This investigation deals in an ex- 

 haustive manner with questions of importance in diseases of plants. 

 It is not sufficient to name a fungus or other cause in investigating 

 disease, and recent work has been much more direcfcd towards investiga- 

 tion of disposition to disease. A plant is said to be immune when it is 

 in such a condition that it is not attacked by a disease-producing agent. 

 Disposition arises from various conditions, such as locality. The 

 author distinguished " disease-receptivity " as a condition of the plant which 

 favours disease. Thus a plant must be frost sensitive before it can 

 be damaged by frost. The results obtained in this paper may be best 

 illustrated by an example. Pine wood is immune against a particular 

 fungus (Ceratostomella) if the volume of air in the fresh wood is below 

 15 per cent. ; with increasing air-volume this fungus grows better and 

 has its optimum growth when the air-content is 42 per cent, of the 

 volume of the wood. This was found to be the case with other fungi, 

 including Nectria, the tree-canker fungus. The results lead to the 

 following general principles : the relationship between immunity and 

 receptivity on the one hand, and air-content on the other, holds good 

 for living plants as well as dead stems ; different parasitic fungi have 

 different air- requirements. — W. G. S. 



Dry-Land^ Agriculture. ( U.S.A. Dept. Agr., Bur. PI. Lid., Bull. 130, 

 October 1908). — This bulletin consists of a series of papers read at an 

 annual meeting of the Co-operative Experiment Association of the Great 

 Plains area, and is a record of the efforts which are being made to remove 

 the difficulties under which cultivators in the semi-arid regions of the 

 Great Plains are labouring. The questions of conservation of moisture, 

 the prevention of soil-blowing, the use of fallows, the proper rotation of 

 crops, and the breeding of grain and fruit which shall be able to resist the 

 unfavourable conditions of the district are all touched upon. Tabulated 

 statistics are also given of rainfall, temperature, comparative moisture of 

 soil, and cost of producing crops at various experimental stations in the 

 regions. — M. L. H. 



Dumortiera, Inflorescence of. By A. Ernst (Ann. Jard. Bot. 

 Buit., xvii., pp. 153-224 ; 7 plates). — Dumortiera trichocephala and 

 D. velutina occur in Java and other islands of the Malay Archipelago. 

 The inflorescence of D. trichocephala is monoecious, or frequently andro- 

 gynous, D. velutina is dioecious, and rarely androgynous. — S. E. W. 



Electrified Plants. By A. Koltonski (Beih. Bot. Centralbl. xxiii. 

 l te Abth. Heft 3, pp. 204-272, figs. 8 in text). 



The paper contains an interesting historical sketch dealing with what 

 has already been discovered in this important subject, followed by a 

 record of the author's careful experiments, which are detailed in 

 fourteen tables. 



The researches of Thouvenin and Pollacci have already proved 

 that under electrical currents the process of assimilation is more active 



