222 SUMMARY OK CURRKNT RESEARCHES RELATING TO 



Notes on Uredineae.* — P. Eennings records a new and harmful 

 species of rust, Uredo Wittmackiana on Epidendrum, from Orizaba, in 

 Mexico. It differs considerably from the species previously found on the 

 plants of this genus. 



Shunsuke Kusano f describes several new forms of Uromyces and an 

 sEciditim on species of Sophora. E. V. Oven $ gives an account of 

 Phragmidium on various kinds of roses. He gives the names of the 

 varieties that were, more or less, subject to attack in the grounds of the 

 Pomological Institute at Proskau. 



W. L. Balls § publishes notes on the infection of plants by rust- 

 fungi. He thinks they are probably in search of watery vapour when 

 they penetrate the stomata of the host. He gives an acount of an 

 experiment he made to test this theory. 



In discussing the occurrence of rusts in the neighbourhood of 

 Toulouse, A. Prunet|| notes that the only one that attained serious 

 proportions during the year li)03 was Puccinia triticina on corn. 



Recent Researches on the Parasitism of Fungi.f — In a discussion 

 of this whole question, Marshall Ward begins with an historical survey 

 of the progressive knowledge of the subjects both of bacteria and fungi, 

 leading on to the great development of the science of Plant Pathology. 

 He then confines himself to a consideration of the Uredineae as parasites, 

 sketches their life-history, classification, the modern view of their 

 sexuality, and the methods of spore distribution. Data are given as to 

 the work of insects in aiding the spread of fungi, and as to the length 

 of time the uredospores retain their vitality, these facts having an im- 

 portant bearing on the theories affecting the unlooked-for appearance 

 of rust in different localities. Specialisation in parasitism is next 

 described and exemplified, and the various explanations of immunity 

 and susceptibility are alluded to. Ward explains and refutes Eriksson's 

 mycoplasm hypothesis, and gives the results of his own observations on 

 infection and on susceptible and immune varieties of plants. In the 

 latter case, though the spores germinated and entered the host plant in 

 the normal fashion, in a few days they died off ; either they were starved 

 for want of food supply, or they were poisoned. He concludes that the 

 phenomena were those of starvation : the hyphas had clumsily killed the 

 plant-cells, instead of delicately tapping them for food, and in turn died 

 for lack of nutrition. Experiments were made to prove this theory, and 

 it was found that the same results were obtained when there was a lack 

 of carbon supply. Small nests of dead, brownish-coloured cells were 

 produced, on which the parasite could not live. The paper concludes by 

 re-stating the facts that go to prove how unnecessary any mycoplasma 

 theory is to explain the appearance of rusts. 



* Gartenflora, 1904, pp. 397-8. See also But. Centralbl., xcvi. (1901) p. 621. 



t Lot. Mag. Tokyo, xviii. (1904) pp. 1-6. See also Centralbl. Bakt., xiii. (1901) 

 p. 782. 



J Naturw. Zeitschr. Land Forstw., 1901, Heft 4-5. See also Centralbl. Bakt., 

 xiii. (1904) p. 784. 



§ New Bhytol., iv. (1905) pp. 18-19. 



|| Assoc. Franc, pour l'Avanc. Sci. Angers, xxxii. (1904) pp. 731-3. See also 

 Bot. Centralbl., xcviii. (1905) p. 98. ^ Ann. Bot., xix. (1905) pp. 1-54. 



