June 17, 1898.] 



SCIENCE. 



825 



motion of Agricultural Science, just re- 

 ■ceived, several of the papers have consider- 

 :able botanical interest. "W. E. Lazenby, in 

 & paper on the ' Annual Growth of Forest 

 Trees,' makes the statement that " the 

 .greatest annual increase in diameter took 

 place on the side most fully exposed to the 

 light, but the greatest growth in length of 

 branches was often on the side not fully 

 •exposed." R. C. Kedzie, in ' The Ash of 

 Epiphytes,' answers the question of the 

 supply of mineral matter to epiphytes by 

 first calling attention to the economical use 

 -of the supply on hand. In speaking of the 

 orchids he says : " Note the thin and 

 papery remains of their leaves, and see how 

 ■carefully mineral matter has been removed 

 from these cast-off clothes of the plant, and 

 how they differ from the leaves of terres- 

 trial plants." He then enumerates the fol- 

 lowing sources of mineral plant food : (1) 

 soil water with which the plants are often 

 watered; (2) winds which carry consider- 

 .able amounts of mineral matter ; (3) the 

 bark of trees which supports the epiphytes 

 and also the pottery, etc., used for supports 

 in conservatories ; (4) very often in nature 

 the roots of orchids grow in a mass of de- 

 •caying leaves which have fallen from the 

 trees and lodged about the plants. B. D. 

 Halsted contributes some ' Notes upon 

 3ean and Pea Tubercles,' which are due to 

 the presence of a parasite, Rlnzohimn legu- 

 minosarum. It was found that larger crops 

 resulted from plantings upon ground known 

 tio be infested with these parasites. 



PAPERS ON THE DISEASES OF PLANTS. 



From Erwin F. Smith we have a paper on 

 Wakker's Hyacinth Bacterium (Abstract in 

 Tree. A. A. A. S. 46 : 274) confirming fully 

 the conclusions reached by Wakker in 

 1882-5, and extending quite materially our 

 knowledge of the organism which is the 

 «ause of the disease. The same author's 

 lecture on ' The Spread of Plant Diseases,' 



before the Mass. Hort. Society and pub- 

 lished in its Transactions, is an excellent 

 popular statement of our knowledge of the 

 means by which certain parasites succeed 

 in getting from one plant to another. He 

 groups them under the following heads : (a) 

 spread by insects ; (b) spread by slugs and 

 snails ; (c) spread through the manure 

 pile; (d) spread byway of the soil; (e) 

 spread by way of seeds, seedlings, buds, 

 tubers, cuttings and nursery stock. In a 

 third paper the same author discusses 

 (Trans. Peninsular Hort. Soc. 1898 : 142) 

 ' Some Bacterial Diseases of Truck Crops,' 

 noticing the ' wilt' of the cucumber, ' Brown 

 Rot ' of the potato, and ' Black Rot ' of the 

 cabbage. 



W. T. Swingle discusses ' The Grain 

 Smuts ' in Bull. 75, U. S. Dept. Agricul- 

 ture, describing the stinking smuts of wheat 

 ( Tilletia foetens and T. trifici) , loose smut of 

 wheat {Ustilago tritiei), loose smut of oats 

 ( Ustilago avenae) , barley smuts ( Ustilago 

 hordei, U. nuda),rje smut (Urocystis occulta) 

 and maize smut ( Ustilago maydis). Directions 

 for treating the seed and grain, including 

 corrosive- sublimate, copper sulphate, for- 

 malin, potassium sulphide, and ' sar ' solu- 

 tion, all of which are intended to kill the 

 spores by poisoning are given. Jensen's 

 hot-water treatment, also, is described and 

 recommended for certain species. 



F. G. Stewart in Bull. 138 of the Geneva 

 (]Sr. Y.) Experiment Station records his re- 

 sults, which show that the popular opinion 

 that the plowing under of green rye will 

 prevent potato scab ( Oospora scabies) is 

 erroneous. He concludes, also, that the 

 potato-stem blight is not due to the pres- 

 ence of fungi or bacteria, but that, on the 

 contrary, it is a pathological condition, not 

 communicable. The practice of some flo- 

 rists of spraying carnations to prevent 

 carnation-rust ( Uromyces caryophylUnus) is 

 shown to be useless ; the salt application 

 neither prevents the rust nor gives the 



