DISEASES OF PLANTS. 773 



forming hyph;i3 are said to become mucilaginous. The author has investigated this 

 phenomenon in order to determine the possible presence of an enzym. He found an 

 aniinoxydase is present in the fungus similar to that which is found in the yeast of 

 beer, and, as in the yeast, it is located in the vacuoles of the cells. As soon as the 

 formation of nuicilage begins in the smut, the production of oxydase is said to cease. 

 The enzym is said to be most active when there is a maximum of metabolism in the 

 cell, and the resting stage of the fungus follows the i:)eriod of mucilaginous formation. 



A new parasite of Trifolium montanum, F. Bubak {Cenibl. BaJct. u. Pur., 2. Abt., 

 S {1902), No. 26, pp. 817-821; abs. in Jour. Roy. Micros. Soc. [Londoni, 1902, No. 5, 

 pp. 586, 587). — An account is given of Urophlyctis bohemica, which attacks plants of 

 Trifolium montanum, causing them to be stunted in their growth and usually prevent- 

 ing their flowering. The leaves and petioles are covered with yellow spots and 

 wart-like excrescences caused by the parasite. These warts are said to be much 

 larger on the petioles than on the blade of the leaf. 



The stem anthracnose of red clover, O. Kirchner {Ztschr. Pflanzenkrank. , 12 

 {1902), No. 1-2, pp. 10-14, figs. ^).— In a previous publication (E. S. R., 14, p. 159) the 

 occurrence of stem anthracnose of clover was mentioned and the cause attributed to 

 Gla'osporium trifolii. Subsequent investigations of the author have shown that the 

 disease in question is not due to that fungus but to an undescribed species to which 

 he has given the name G. caulivorum, n. sp. The characteristics of the disease are 

 given and the fungus is technically described. 



■Urophlyctis, a fungus causing galls on the roots of alfalfa, P. Magnus {Bar. 

 Beut. Bot. GeselL, 20 {1902), No. 5, pp. 291-296, pi. 1; abs. in Jour. Roy. Micros. Soc. 

 [^Londmi], 1902, No. 5, p. 586). — Descriptions are given of galls produced on alfalfa 

 roots which were hitherto ascribed to the presence of the fungus Cladocliytrium 

 alfalfiv, but which the author believes belongs to the genus Urophlyctis. The galls 

 occur as small excrescences on the larger roots. The disease occurs in damp soil 

 only and is fatal to the plants. It was first described by Lagerheim from Ecuador, 

 from where it has been recently brought to Alsace. 



On the parasitism of Pseudomonas destructans, M. C. Potter {Proc. Boy. Soc. 

 [London], 70 {1902), No. 464, PP- 392-397, figs. ^).— Since the publication of the 

 author's paper on a bacterial disease of the turnip (E. S. R., 13, p. 467) his investiga- 

 tions have been continued, and the action of the cytase and toxin upon the living 

 cells has been studied, and he has succeeded in tracing the passage of the bacteria 

 through the cell walls into the cell. He has found that through the secretion of 

 cytase and a toxin the parasitic action of the bacteria is comparable with that of cer- 

 tain parasitic fungi. In his previous investigations the attack of the organism could 

 always be traced to a wound, and he has since found that the 1)acteria do not have 

 the power to penetrate the cuticle of the mature epidermis. The parasite can, how- 

 ever, readily effect an entrance into its host through the undeveloped epidermis of 

 young and tender structures. Whether in the case of Pseudomonas destructans the 

 toxin or cytase is the first excretory product it is impossible to say, but the latter 

 produces the first visible effect and is believed to prepare the way for the rapid action 

 of the toxin. 



The root rot of tare, J. G. Smith {Hawaii Sta. Bui. 2, pp. 21, figs. 2) . — An account 

 is given of the causes and means for prevention of a destructive disease that threatens 

 the extinction of the taro crop of Hawaii. The taro ( Colocasia antiquorum escidentum) 

 is one of the principal food plants of the native Hawaiian, and its long cultivation 

 has apparently deteriorated the stock to a considerable extent. Wherever the taro 

 is grown entirely under irrigation it suffers severely from the disease known as taro 

 rot. This is characterized by the shortening and early maturing of the root stocks. 

 It was found that the rot is readily spread by the planting of diseased suckers. It 

 was also found that by planting suckers free from disease and securing a good circu- 

 lation of irrigation water, together with the application of proper fertilizers and an 

 occasional rotation of crop, this disease ma}' be to a great extent prevented. 



