188 PATHOLOGY [BoT. Absts., Vol. Vll, 



chilling included trials in accurately controlled freezing chambers where the temperature 

 could be dropped at any desired rate. There is variation in individual susceptibility of 

 tubers; in general, frost necrosis appears following exposure to about — 10°C. for 1 hour, 

 —5° for 2 hours, or to slightly below —3° for several hours. While the actual freezing tem- 

 perature is near 1°C., super-cooling to —3° to —5° is necessary, the degree of this being greater 

 with slow rate of temperature drop. The conditions of turning sweet and of freezing solid 

 are also described. Neither variety, size, maturity, nor relative tuber turgidity seems to 

 influence frost necrosis. Sprouts are relatively resistant, but start slowly. Therefore, it 

 is not advisable to use frosted potatoes for seed. Frost necrosis symptoms are not inherited. 

 — R. E. Vaughn. 



1268. Lee, S. C. Electrical treatment of seed. Agric. Gaz. Canada 7: 248-249. 1920.— 

 See Bot. Absts. 7, Entry 625. 



1269. Manaresi, Angelo. Sui danni prodotti ai fiori degli alberi fruttiferi dalle gelate 

 primaverili in genera e da quelle in particolare dei giorni 28, 29, e 30 marzo 1918. [Damage to 

 flowers of fruit trees by spring frosts and in particular the frosts of March 28, 29, and 30, 1918.] 

 Rev. Patol. Veg. 10: 1-26. 1919.— See Bot. Absts. 7, Entry 986. 



1270. Moore, V. A. Principles of Microbiology. 8vo. 506 p. New York, 1918.— A 

 treatise on bacteria, fungi, and protozoa pathogenic to domesticated animals. 



1271. Neger, F. W. Die RoUe des Lichtes und Chlorophylls bei der Entstehung von 

 Rauchschaden an griinen Pflanzen. [The role of light and of chlorophyll in the initiation of 

 smoke injury to green plants.] Zeitschr. Forst-u. Jagdw. 48: 624-635. 1918.— Abst. in Zentbl. 

 gesamte Landw. 1, Entry 445. 



1272. Rayner, M. C. Mycorrhiza and the Ericaceae. [Abstract.] Rept. British Assoc. 

 Adv. Sci. 1919:332. 1920. 



1273. Smith, Erwin F. An introduction to bacterial diseases of plants. 23 X lo cm., 

 XXX + 688 p. 453 fig. and frontispiece. W. B. Saunders Co. : Philadelphia, 1920.— "Manu- 

 scipt of this book was completed for publication in 1915 and, in general, that year may be 

 taken as the date of the outlook, but here and there, where it seemed most necessary, it has 

 been revised down to the end of 1919." — The book has been made primarily for laboratory 

 use under the guidance of a competent teacher. It is the "result of 35 years of reading and 

 25 years of diligent laboratory and field investigation."— Part 1 (75 p.) is a conspectus of 

 bacterial diseases of plants under the topics: distribution, period of susceptibility, infection 

 incubation, recovery from disease, transmission of pathogene, morphology and physiology, 

 of parasite, action of parasite on host, host reaction, methods of control. Part 2 (56 p.) 

 deals with technique: apparatus, culture media, isolation, inoculation, sectioning, staining, 

 illustrating, cataloging, etc. Part 3 (341 p.) is devoted to an extended account of the diseases 

 caused by the following organisms: Bacillus tracheiphilus, Bad. campestre, Aplanobacter 

 stewarti, Bad. solanacearum, Aplanobacter michiganense, Bacillus carotovorus, B. phyto- 

 phthorus, Bad. phaseoU, Bad. maculicolum, Bad. malvacearum, Bad. mori, Bacillus amylo- 

 vorus, Bact. savastanoi, and Bact. tumefaciens . Part 4 (160 p.) deals with tumors, tumor 

 formation, experimental teratoses. Part 5 (30 p.) contains suggestions for students about 

 study, experimentation, interpretation, presentation, ethics, etc. — D. Reddick. 



1274. WiELER, A. Rauchschaden bei Kokereien. [Smoke injury from coke ovens.] 

 Jahresb. Vereinig. Angew. Bot. 16: 64-76. 1918.— Abstract in Zeitschr. Pflanzenkr. 30: 

 22-23. 1920. 



1275. Zavitz, C. a. Systematic experiments. Agric. Gaz. Canada 7: 244-246. 1920.— 

 See Bot. Absts. 7, Entry 684. 



