NOTES AND ABSTRACTS. 



509 



centres are described, and a history and description given of each 

 variety of tobacco grown in Ohio. — M. L. H. 



Tobaccos of the United States. By E. H. Mathewson (U.S.A. 

 Dep. Agr., Bur. PL Ind., Bull. 244 ; Nov. 23, 1912 ; plates and maps). 

 — A full description and statistical account of the tobacco crop all 

 over the United States. The bulletin is written more from the point 

 of view of the trader and Revenue Department than of the agricul- 

 turist, but it describes every strain of tobacco grown in North America, 

 all the different methods of curing and preparing the leaf for market 

 which produce the different brands, with an explanation of and a 

 suggested origin for the trade names borne by the crop in every stage 

 of its growth. The introduction gives a general history of tobacco- 

 growing in America, and refers to the various alterations and vicis- 

 situdes which the export trade has undergone through the policy of 

 Great Britain in the early Colonial days, through over-produc- 

 tion, through wars at home and abroad, and through European 

 complications. 



Tables are then given of the yearly output of each State, and the 

 crop is analysed into wrapper, leaf-binder, filler plug tobacco, chewing 

 tobacco, &c, this part of the subject being illustrated by large folding 

 maps coloured in different shades to show the dominant type of 

 tobacco grown in each district. 



There are many illustrations of the leaf in all stages of preparation, 

 of growing and harvesting operations, and of the various styles of 

 building and appliances used in the different centres. — M. L. H. 



Transpiration and Varying Density of Solution. By George 

 Bonyoncos (Beih. Bot. Cent. Bd. 29, Abt. 1, Heft 1, pp. 1-20 ; with 

 3 figs.). — The author grew wheat seedlings both in water and in sand 

 and soil cultures, and used the following varying concentrations of a 

 complete nutrient solution: — 93-5, 187-5, 375, 750, 2250,4500 parts 

 per million. 



He found that in all cases both the rate of growth and grams of 

 dry matter produced (after the first four or five days) increased with 

 increase in density of the solution. The transpiration of the seedlings 

 is certainly affected by the degree of density of the nutrient solution. 

 The number of transpirations required for every gram of dry matter 

 formed increased with the density from 0 to from 93-5 to 375 parts 

 per million, but then decreased. 



The author suggests that the osmotic strength of the cell-sap 

 increases with the density of the solution, and tested this theory by 

 extracting the cell-sap and examining its osmotic strength by the 

 electrical resistance as found by means of the Wheatstone bridge 

 and by determination of the freezing-point. 



He found a greater concentration of the cell-sap with an increase 

 in density of the solution. 



Dilute solutions stimulate transpiration. The actual dry matter 

 produced was largest in the plants grown in solutions, and larger in 



