DISEASES OF PLANTS. 987 



short branches, the violet coloration <>f normally green tissues, the abnormal forma- 

 tion of chlorophyll in tissues not usually containing it, the formation of starch in 

 abnormal quantities and in unusual tissues, the increase of cell division, the modi- 

 fication of tissues, reversion of flower parts, etc. 



A large number of inoculation experiments were performed to discover the phe- 

 nomena of specialization, the conidia of the fungus being reciprocally transferred 

 from host to host, various methods being employed. Attempts were made to intro- 

 duce C. tragopogonis from salsify, hut negative results were obtained with cruciferous 

 plants, although Scorzonera hispanica was successfully inoculated. Successful experi- 

 ments were made in which the disease was caused on several species of plants with 

 oospores from Lepidium sativum. 



The inoculation experiments with cruciferous host plants, whilegiving many nega- 

 tive results, are held to show the existence of a single species of fungus and to proba- 

 bly indicate the differentiation of at least 2 biological groups of cruciferous plants, 

 one containing the species of Capsella, Lepidium, and Arabis, the other Brassica, 

 Sinapis, and probably Diplotaxis. 



The downy mildew of cucurbits in Hungary, G. Linhart (Ztschr. Pflanzen- 

 krank., 14 (1904), No. 3, pp. 143-145). — The occurrence of the downy mildew of 

 melons, cucumbers, and other cucurbits in Hungary is noted. In some regions as 

 high as 80 per cent of all cucurbits were destroyed by this fungus. For its preven- 

 tion the author recommends thorough spraying with 1 to \\ per cent solutions of 

 Bordeaux mixture. 



Attention is called to a note by Rostowzew in which it is claimed that the fungus 

 is not a true Peronospora and the name Pseudoperonospora cubensis is proposed for it. 



Monilia diseases of fruit trees, J. Ritzema Bos (Tijdschr. Plantenziekten, 9 

 (1903), pp. 125-146, pis. 3, figs. 10). — Descriptions are given of the brown rots of 

 fruits due to Monilia spp. The usual form of fungus occurring on apples, pears, and 

 other pomaceous fruits is said to be M. fructigena, while that naturally parasitic on 

 cherries, plums, peaches, and stone fruits is M. cinerea. The author discusses the 

 possible relationship between these two species and shows that many intergrading 

 forms can be found and cross inoculations made under artificial conditions. Under 

 natural conditions the differences seem sufficient to separate the parasites as distinct 

 forms or races of fungi. 



Investigations concerning olive bacteriosis, R. Schiff (Centbl. Bakt. u. Par., 

 A AbL, 12 (1904), No. 6-8, pp. 217, 218). — A preliminary report is given on some 

 bacteriological investigations on Bacillus olese, the cause of the disease of olives 

 known as bacteriosis. The organism is said to be a polymorphous one, forming in 

 the tissues of the host short, rounded bacteria, but when cultivated upon artificial 

 media it exhibits a number of modified forms. Some of the special modifications 

 due to the substratum on which the organism is grown are described, and notes are 

 given on the. action of the bacillus on the cell centents and tissues of the host plant. 



A disease of the olive tree, U. Brizi (Separate from Bol. Uffic. Min. Agr., Ind. e 

 Com. [Rome], 1903, pp. 40, pis. 5; abs. in Bot. Centbl., 96 (1904), No. 51, p. 643).—A 

 description is given of a disease of the olive tree known as "brusca" which is 

 attributed to the fungus Stictis panizzei. The history and characteristics of the 

 disease, its effects and conditions of development, together with a botanical study of 

 the fungus, are given. 



Two new diseases of figs, R. Farneti {Atti Inst. Bot. Univ. Paiia, 2. ser., 8 

 (1904), pp. 513-517 ). — Notes are given on two new diseases of figs caused by attacks 

 of Atternaria fici, n. sp., and Cladosporium sicophilum, n. sp. The fruits are the por- 

 tions attacked, and considerable injury is reported as following the appearance of 

 the disease. Technical descriptions are given of both fungi. 



A gum disease of grapes, L. Manoin and P. Viala ( Rer. 17/., ..'3 ( 1905), No. 577, 

 pp. 5, 6, pi. 1). — A description is given of the formation of gum on grapes, which so 



