1130 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



As to the actual cause the author says : " Of the various theories, we 

 have found no other to have so much in its favour as that which says the 

 ultimate cause of the upward movement of water in the wood to replace 

 the loss by transpiration is the pressure of the atmosphere against the 

 water absorbed by the roots. The kernel of the whole question is, Why 

 is this atmospheric pressure (said to push water up only 10 m ) exhausted 

 so slowly by the ascent of the tree that, whatever height is reached, 

 and however rapidly and forcibly water may be drawn from the wood, 

 some pressure always remains ? Of two physiological factors — 

 removal of water by transpiration and the pressure of the atmosphere— 

 we know that in the entire absence of either the water does not rise." 

 He concludes with the words : " Much further than this we cannot go." 



G. H. 



On the Origin of Tubers. 



Tuberisation, Studies On. By M. Noel Bernard (Rev. Gen. Bot. 

 t. xiv., 1902 ; with plates and figures in the text). — The author endeavours 

 to show that the tubers so characteristic of many plants, e.g. Potatos, 

 Orchids, &c, owe their origin to a reaction on the part of the plant to 

 a fungus, apparently belonging or related to Fusarium. The fungus 

 is found in the roots, and M. Bernard finds that the time of tuberisation 

 bears a relation to the period at which infection in the soil takes place. 



Many instances are known of the reactions of plants to other organisms, 

 as the result of which definite structural features become apparent, as for 

 example in the case of the production of galls. It may, however, be 

 doubted whether botanists will be prepared to accept the author's con- 

 clusions in the absence of full experimental evidence based on rigid 

 methods of cultivation of the affected plants when the fungus is excluded 

 from them as well as when it is present. The alleged time relation be- 

 tween tuberisation and infection may only be a circumstance of a corre- 

 lative character, and may not in any way indicate a causal connection 

 such as M. Bernard supposes. — J. B. F. 



Classification of Uredin.e. 



Uredinae on Umbelliferae, Classification of, by Lindroth. By 



C. B. Plowright (Garri. Chron. No. 825, p. 282; Oct. 18, 1902).— The 

 writer has extracted from Lindroth's work on these fungi a list of the 

 British species, seventeen in number, and says the above-mentioned work 

 " consists of a classification and description of all the known species, 

 some eighty-eight in number, of Uredines which attack umbelliferous 

 plants." The Puccinice, which are by far the most numerous, are divided 

 into four groups : (1) those with reticulate teleutospores ; (2) with 

 verrucose ; (8) with smooth ; (4) with well-developed teleutospores, 

 thickened above, on coloured persistent stems; and (5) a group which 

 includes four exotic Lcpto -puccinice. — G. S. S. 



Nature of Stem Formation. 



Vascular System of the Stem, the Nature of, in certain Dico- 

 tyledonous Orders. Note by W. C. Worsdell (Ann. Bot. vol. xvi., No. 64, 

 p. 599). Abstract of paper read before Section K of the British Association, . 



