356 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



to 6 gallons of water). Potassium nitrate and phosphate of the. above 

 strength are also beneficial. 



The unpopularity of the Cupid sweet pea is due to the fact that 

 the flowers are on short stems, and also that the White Cupid did 

 not germinate well. The black seeds germinate freely. In a wet 

 season, the flower -buds drop off. 



Dwarf sweet peas require a rather dry, moderately rich soil, and 

 a dry, hot season. Withered flowers and pods must be promptly 

 removed. — S. E. W. 



Sweet Potato, Black Rots of. By J. J. Taubenhaus {Phyto- 

 pathology, iii. p. 159, June 1913 ; figs.).— There is more than one 

 form of black rot in the sweet potato, the commonest being due to 

 Sphaeronema fimhriatum, and not causing the rotting of the whole root. 

 Charcoal rot affects the whole root, and is due to Sclerotium hataticola 

 n. sp. There is a third form in which the tubers show dark shrivelled 

 patches, over which are scattered numerous pycnidia due to the fungus 

 Lasiodiplodia tuhericola and called the Java rot. — F. J. C. 



Sweet Potato, Foot Rot of. By L. L. Harter [Jour. Agr. 

 Research, i. pp. 251-274 ; Dec. 1913 ; plates). — This disease has already 

 been referred to in these abstracts (Jour. R.H.S. vol. xxxix. p. 804). 

 The present communication gives a fuller description both of the disease 

 and of the organism producing it (Plenodomus destruens) than was 

 contained in the former paper. — F. J. C. 



Temperature and Growth. By B. E. Livingston and G. J. 

 Livingston {Bot. Gaz. Ivi. pp. 349-375, Nov. 1913 ; with 3 maps). — 

 It has been found by Price that the time required from the resting 

 period to the opening of the flower-bud in the case of various fruit 

 trees is reduced by about one-half for each rise in temperature of 

 10° C. So, also in the growth of maize seedlings, the rate of growth is 

 nearly doubled for each rise of 10° C. 



The authors assumed, therefore, 2 to be the temperature coefficient 

 for every rise of 10° C. in temperature. They calculated these 

 coefhcients for a very large number of stations over the whole of the 

 United States, using Bigelow's daily normal temperatures (published 

 by the Weather Bureau), but only for the interval between the last 

 spring and the first autumn frosts. 



The results are shown in one of the maps. Another map shows 

 results obtained by simply adding up the normal daily mean 

 temperatures (Van 't Hoff, Arrhenius' system). 



In a broad and general way, and for most of the United States, the 

 climatic zones shown in the two maps agree with one another. A 

 third map shows the distribution of the ratios of the direct adding 

 to the efficiency summation data. — G. F. S. E. 



Thismia. By Norma E. Pfeiffer {Bot, Gaz. Feb. 1914, pp. 122- 

 135 ; 5 pis.). — The author found in the open prairie near Chicago a new 



