140 JOURNAL OF THE EOYAL HORTICULTURAL SOCIETY. 



mixtures are improperly made, the quantities to be used being guessed 

 at, and the materials are mixed in the wrong way.— F. J. C. 



Potato: Surface Spotting- of Tuber. By W. J. Morse {U.S.A. 



Exp. Stn. Maine, Bept. 1907, pp. 321-322).— Black spots on the surface 

 of the tuber from the size of a small pea to half -inch in diameter, on which, 

 when isolated, the fungus Phytophthora infestans developed. It is recom- 

 mended that such tubers be not planted. — F. J. C. 



Prairie Grass of Dakota, Floral Succession in the. By Le Roy 



Harris Harvey (Bot. Gaz., August 1908, pp. 81-109 ; with 3 figures).— The 

 author describes three distinct stages, early spring, spring, and early summer 

 (second week in June to end of July) in the flora of South-Eastern South 

 Dakota. 



The climatic features of each of these successive flowering periods are 

 given very fully, and the differences due to the various exposures and to 

 the positions of the plants (as at the base or toward the crest of the ridges) 

 are carefully distinguished. 



This area seems to show the steady colonization of part of the prairie 

 by the forest flora of the south-eastern district, to which region, in the 

 author's opinion, it had been driven back during the glacial period. He 

 considers that the " Poa pratensis sod " is followed and occupied first by 

 the Wolfberry shrub (Symphoricarpus occidentalis). This is the forerunner 

 of Bhus glabra. These two shrubs are then dispossessed by Quercus 

 macrocarpa and Ulmus fulva associations as the forest pushes out on the 

 prairie. 



To the west and south-west of the region the plain or prairie type 

 predominates and is of a more xerophytic character, becoming more and 

 more arid and desert-like towards the west. 



The author does not think that the absence of trees on the natural 

 prairie is due so much to forest fires, but rather to the lack of soil moisture, 

 and to the dense sod, which make it difficult for the seeds of trees to 

 germinate. Seedlings will also hardly resist the severity of their first 

 winter. This paper is a very interesting one, although a few unusual 

 technical terms are at first disheartening to non-botanical readers. 



G. F. S.-E. 



Preservative Treatment of Loblolly Pine Cross-arms. By 



W. F. Sherfesee (U.S. Dept. Agr. Forest Service, Circ. 151). — An 

 account of the seasoning and grading of the timber of the Loblolly Pine, 

 which has been found so useful for the making of cross-arms. The 

 length of time required for air-seasoning depends largely on the character 

 of the timber, atmospheric conditions, and the manner in which it is piled, 

 all of which are fully described in this pamphlet. Several useful tables 

 and illustrations of the best methods of piling cross-arms are also given. 



A. D. IF. 



Protoplasmic Streaming' and Plasmolysis (Bot. Gaz. July 1908, 

 pp. 50-56). — Miss Grace M. Bushee and W. Y. V. Osterhout have short 

 papers on those subjects in this magazine. The former measured the rate 

 of streaming in millimetres a minute in thirty-six common greenhouse 

 plants. She recommends especially Gloxinia spcciosa (cell of hair from 



