No. 1, August, 1921] PATHOLOGY 63 



agencies in which parasites are at least secondary. For the most part the book aims to give 

 a short presentation of the material for teaching purposes, rather than a fuller presentation, 

 such as given by Sorauers' Handbuch der Pflanzenkrankheiten, I. The book, however, 

 uses the plates from the Sorauer text and the arrangement of the material is similar. Follow- 

 ing a general introduction dealing briefly with the history of the subject, the concept of 

 disease, and the causes of plant disease, the relation of climate and geographical location and 

 plant disease is outlined. In the main body of the work the form of presentation is largely 

 descriptive, and the material is presented under 6 topics: (1) Unfavorable soil; (2) air con- 

 ditions (moisture, dryness, wind); (3) heat and light; (4) wounds; (5) injurious gases and 

 liquids; (6) enzymatic diseases (panachure, mosaic, gum and resin flow). The book is in- 

 dexed and some literature references are made. — G. H. Coons. 



419. HuDiG, J., en C. Meyer. De Veenkoloniale haverziekte III. [The marsh-colony 

 disease of oats, III.] Verslag. Landbouk. Onderzoek. Kijkslandbouwproefsta. 23: 1-39. 

 Fig. 1-15. 1919. — In pure quartz sand free from organic substances, oats may be grown in 

 a mixture of salt solutions which are basic, though the plants should not have too long a period 

 of growth. An addition of roots of oats, stalks of oats, and cotton batting to the sand in 

 quantities of 0.75-2 per cent causes the disease, independent of early or late sowing or cold 

 or warm weather. The presence of a basic fertilizer is necessary. Under the same conditions 

 extracts of roots of oats have the same effect as added pieces of roots. Leaves of oats added 

 in the same quantities have a favorable effect upon the plants. Sand cultures to which acid 

 salts or nitrites are added never develop the disease. Manganese sulphate appears best suited 

 to combat the disease. [See also following entry.] — J . C. Th. Uphof. 



420. HuDiG, J., en C. Meter. De Veenkoloniale haverziekte IV. [The marsh-colony 

 disease of oats, IV.] Verslag. Landbouwk. Onderzoek. Kijkslandbouwproefsta. 23: 128- 

 158. Fig. 1-8. 1919. — The disease, which may become very dangerous, appears as a striped 

 chlorosis and is caused by alkali in the soil solution. A decoction of decomposing cellulose 

 in sand containing alkali may cause the disease; potato starch has the same effect. Material 

 containing cellulose is harmless if the environment is acid; also if manganese sulphate or 

 sulphur is applied. Sulphur flour is oxidized to sulphuric acid in aerobic sand cultures. 

 [See also preceding entry.] — /. C. Th. Uphof. 



421. Jagger, Ivan C. A transmissible mosaic disease of lettuce. Jour. Agric. Res. 

 20: 737-739. PI. 87. 1921.— The disease occurs in Florida, North Carolina, and New York.— 

 Romaine lettuce (Paris White Cos) and head lettuce (Big Boston) are affected. Typical 

 mottling and wrinkling occur. All variations are found from very slight mottling with no 

 apparent injury to pronounced mottling and very evident dwarfing of plants. Transmission 

 experiments with the aphid, Myzus persicae, were successful. — D. Reddick. 



422. NowELL, W. The red ring disease of coco-nut palms. West Indian Bull. 18: 73- 

 76. 1920. — A more complete report is given on infection experiments carried out in Grenada, 

 West Indies, which supplements earlier notes on the same subject (see Bot. Absts. 4, 1327). 

 The results support the idea that infection occurs in the leaf bases, and may frequently take 

 place by way of the small cracks formed by the bending outwards of the leaf as it matures. 

 This would render untenable a previous hypothesis that infection takes place at an early 

 age, the effects manifesting themselves only on the maturing of the tree. — /. S. Dash. 



423. OoRTwiJN BoTJEs, J. G. De bladrolziekte van de aardappelplant. [LeafroU disease 

 of the potato plant.] 136 p. 8 pL Wageningen, 1920. — The primary symptoms can easily be 

 mistaken for those of other diseases, but the secondary ones are definite and in this period 

 occurs the rolling up of the leaves. On infested plants grown from healthy tubers, symptoms 

 often can not be noticed during the 1st period of growth. The necrosis of the phloem is typical 

 and this is accompanied by a retardation in the transfer of starch. External symptoms can 

 be observed about 10-30 days after the tubers start growth. LeafroU disease is contagious; 



