188 PATHOLOGY [Bot. Absts., Vol. VI, 



richer) exuded by the pistil of the female flower. One embryo is usually produced, but 

 investigations have shown germination occasionally from two or more. The seed is "shot-out" 

 of the ripe fruit; the propulsive force being obtained by tensions developed in the fruit mem- 

 brane The seed is provided with mucilaginous threads, which balance the seed in flight, 

 enable it to adhere to its host, and also act as moisture absorbents. Arceuthobium differs 

 from other Loranthaceous parasites in its greater moisture requirement for germination. 

 Although a point under dispute, the author contends that shedding of old sprouts is a regular 

 process. The plant protects itself against excessive transpiration by the formation of an 

 enduring row of epidermal cells, which may become several rows thick. The fibro-vascular 

 bundles are either isolated or in groups separated by woody tissue. The irregularities in the 

 anatomy of Arceuthobium sprouts are evidently occasioned by the large percentage of non- 

 woody, divisible parenchyma, especially in the pith and medullary rays, and in the parenchyma 

 between the bundles in the wood. This parenchyma increases in different degrees. The death 

 of young shoots of infected trees is sometimes caused by this parasite; and whole trees may be 

 killed. It causes injury not only by taking water and food from the plant, but by the chemical 

 decomposition of cells, and by the mechanical rupturing of cell membranes. — J. Roeser. 



1290. van Overeem, C. Uber zwei wenig bekannte Schmarotzer von Discomyceten. 

 [Two little-known parasites of discomycetes.] Hedwigia 61 : 375-379. 1 fig. 1920. 



1291. Waldron, J. W., A. Gartley, C. R. Hemenway, J. N. S. Williams, G. P. Wilcox, 

 T. H. Petrie, and H. P. Agee. Report of the committee in charge of the Experiment Station. 

 Rept. Exp. Sta. Hawaiian Sugar Planters Assoc. 1919: 1-49. 1920.— See Bot. Absts. 6, Entry 

 901. 



1292. Washbtjrne. J. N. White pine "flu." Amer. Forestry 26: 343-345. 8 fig. 1920. 

 — Concerns the white pine blister rust and the pinon pine rust. Popular. — Chas. H. Otis. 



1293. Wells, B. W. Early stages in the development of certain Pachypsylla galls on Celtis. 

 Amer. Jour. Bot. 7: 275-285. / pi. 1920. 



1294. Wober, A. Versuche zur Bekampfung des roten Brenners und des falschen Mehl- 

 taues der Reben im Jahre 1919. [Experiments in the control of red blight and downy mildew 

 of the vine in the year 1919.] Zeitschr. Landw. Versuchsw. Deutschosterreich 23: 1-6. 1920. 

 — For the prevention of red blight (Pseudopeziza tracheiphila) , painting the vines with 40 

 per cent iron sulphate solution during the winter followed by four applications of 1.5 per cent 

 Bordeaux mixture during the growing season, gave the best results. Good results also were 

 obtained by the use of commercial colloidal preparations of copper. Omission of the winter 

 treatment lessened the control somewhat. — For the prevention of doAvny mildew (Plasmopara 

 viticola), four spray applications were made, beginning just before the looming period. Good 

 results were obtained by the use of Bordeaux mixture, various commercial colloidal prepara- 

 tions of copper, a mixture containing copper sulphate, zinc sulphate and lime, and a colloidal 

 silver preparation. — John W. Roberts. 



1295. Wormald, H. The "brown rot" diseases of fruit trees, with special references to 

 two biologic forms of Monilia cinerea Bon. II. Ann. Botany 34: 143-172. April, 1920. — 

 Continuing his work of comparing the organisms bringing about the different types of "Brown 

 Rot" on fruits in England, the author in this contribution determined that the strain of Moni- 

 lia cinerea infecting flowering shoots and cankers of apple trees (forma mali) differs from the 

 organism isolated from plum (forma pruni) in its greater capacity to secrete an enzyme which 

 oxidizes tannin. The oxidizing enzyme produced freely by M. cinerea forma mali was demon- 

 strated by use of gum guaiac emulsion as well as by pyrogallic acid. The enzyme did not show 

 any action upon tyrosin or hydroquinone but did produce a brownish-yellow color in solutions 

 of tannic, gallic and pyrogallic acids. It was produced by "forma ?nali" in liquid culture 

 media, infected fruits and spurs of apple and its presence is correlated by the writer with 



