NOTES AND ABSTRACTS. 



897 



evaporation ; (2) to prevent the plant-food in solution being carried by 

 excessive capillary rise too near the surface above the zone of roots, and 

 to obviate its being left by evaporation where the heavy rains will dissolve 

 it and carry it into the surface drainage ; (3) to give better circulation of 

 air to the soil, which roots and soil organisms require ; and (4) to allow 

 every heavy rain at once to enter the soil deeply, and thus lessen the loss 

 of fertility by surface washing. Tables are given showing the results of 

 experiments in different types of soils, such as sandhill, selma silt loam, 

 pocoson, Norfolk sandy soil, £c. Results are also given of washing the 

 surface inch of soils with distilled water for three minutes, the nitrates 

 phosphates, and sulphates being recovered to the extent of hundreds of 

 pounds per acre. From the tables given it is seen that relatively much 

 larger amounts of each of these salts have been carried in the surface inch 

 of soil in the cases where the soil has not been left loose. The granular 

 structure and porosity of different soils are considered. Most valuable 

 results are given in the article, and tables set out to illustrate the results 

 of the experiments. — V. J. M. 



Soil Physics to Plant Growth, An Experiment on the Rela- 

 tion of. By B. E. Livingstone and G. H. Jensen (Bot. Gaz. xxxviii. 

 No. 1, p. 67). — The object of the experiment was to discover the 

 different effects of the size of the particles of soil in retaining water. 

 Crushed quartz was used in three grades, the finest having an average 

 diam. 0-02 mm., the medium 0-6* mm., and the coarsest T15 mm., the 

 necessary nutritive salts being added alike to each. Photographs show 

 the final results. Nine wild flowers were grown in each tub filled with 

 the above. In the finest soil all the plants were in great vigour ; in the 

 medium soil they were much reduced ; while in the coarsest soil several 

 were dead and all more or less stunted. — G. H. 



Solanum Commersonii {Rev. Hort. pp. 402-3, Sept. 1, 1904).— 

 Some interesting remarks re this Potato species and its capacity of im- 

 provement by culture. The flowers afford a sweet perfume like Jessamine, 

 the foliage serves as forage, and the tubers for food ; apparently a very 

 valuable introduction. — C. T. D. 



Solanum Commersonii and its Varieties, from their Bearing 1 

 on the Origin of the Cultivated Potato. By E. Heckel (Compt. 

 Bend. Nov. 1904, p. 887). — Seven species of tuber-producing Solanum, 

 also several others grouped by Baker as simple varieties oiS. tuberosum, 

 were cultivated. Out of these only one species — S. Commersonii — survived 

 after eight years of cultivation. This species presented the phenomena of 

 variation and of productivity in a manuer which suggests a solution of the 

 much-disputed question as to the origin of the varieties cultivated under 

 the name of S. tuberosum. 



In support of this statement the following observations are recorded. 

 During a period of two years S. Commersonii did not show the slightest 

 variation when grown in the Marseilles Botanic Garden ; but all at once, 

 on changing the climate and conditions — to wet soil — it passed through 

 a sequence of variations to the wild form. Between some of the varieties 



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