AuGi'ST 4, ]905.] 



SCIENCE. 



149 



through the bottom. In this way the plants 

 were kept abundantly supplied with fresh 

 solution. At the end of this period the dif- 

 ferences in growth were very marked, there 

 being a gradual increase in growth from those 

 flooded with the weakest to those flooded with 

 the strongest solution, the latter culture being 

 by far the best of the series. This experi- 

 ment was repeated as experiment XI., and in 

 addition the solution of 75 parts per million 

 was increased in concentration by the addi- 

 tion of 305 parts per million of sodium chlo- 

 ride and also of an equal amount of calcium 

 chloride. The baskets were flooded with the 

 solution daily for 18 days, at the end of which 

 time they were sealed over the top with paper 

 and paraffin to prevent evaporation from the 

 surface of the sand, a small opening being 

 left for the stems. The transpirations were 

 then taken for two days and are given in 

 Table III., together with the relative figures 

 obtained by considering the transpiration of 

 the first culture as 100. The figures are rela- 

 tively proportional to the size of the plants at 

 this time. 



Here the same gradation of growth is ap- 

 parent in the series of different concentrations 

 of nutrient solution as was observed in experi- 

 ment XL Furthermore, addition of either 

 sodium chloride or calcium chloride produces 

 a marked increase in growth. This test was 

 repeated as experiment XII., this time taking 

 as controls the nutrient solution in concentra- 

 tions of 75 and 750 parts per million and in- 

 creasing the concentration of separate portions 

 of the weaker of these by addition of 675 parts 

 per million of sodium chloride, of calcium 

 sulphate and of sodium phosphate, respect- 

 ively. The cultures were treated in the same 

 manner as in experiment XL until the twenty- 

 seventh day, after which they were sealed and 

 weighed. The transpiration for two days is 

 given in Table IV., together with relative 

 figures obtained in the usual manner. 



From the last three experiments it appears 

 that in quartz sand as well as in a free solu- 

 tion the concentration of dissolved salts is a 

 factor in determining plant growth, independ- 

 ently of any changes in the nutrient value of 

 the medium. This may be so in ordinary 



soils, as well, although of course the problem 

 here is complicated by the presence of undis- 

 solved nutrient materials in the soil. Ferric 

 hydrate and carbon black have the same bene- 

 ficial effect when mixed into many infertile 

 soils as has been described for nutrient solu- 

 tions, so that it appears that the above-men- 

 tioned hypotheses regarding toxic materials 

 may be applied here also. 



For many years experiment station workers 

 have been studying the problem of the re- 

 placement of potassium by sodium compounds 

 in commercial fertilizers. Marked increases 

 in crop yields have been obtained by the addi- 

 tion of sodium chloride to soils receiving only 

 a small amount of potassium. From the ex- 

 periments here described it appears that this 

 increase in yield may not at all be directly 

 connected with any change in the nutritive 

 content of the soil. 



J. F, Breazeale. 



Bureau of Soils, 

 _U. S. Department of Agriculture, 

 Washington, D. C. 



the classification of the ordovician rocks 

 of ohio and indiana. 



A MORE detailed study of the great mass of 

 strata included in the Cincinnatian series of 

 the Ordovician rocks of Ohio, Indiana and 

 Kentucky makes necessary the classification 

 of these strata into divisions and subdivisions 

 of the series. This service was rendered by 

 Mr. John M. Nickles in his papers on the 

 Geology of Cincinnati^ and on the Richmond 

 group in Ohio and Indiana.^ 



In the twenty-eighth annual report of the 

 Indiana Geological Survey, published in 1903, 

 the classification proposed by Nickles was 

 adopted without change. Since the publica- 

 tion of this report, however, several changes 

 in the nomenclature have seemed advisable. 

 Some of these are due to the practise, which 

 recently has become more general, of adopting 

 distinct names for formations which formerly 

 were considered approximately identical, when- 

 ever a study of their fossil faunas indicates 

 that these formations were deposited in zoolog- 



^ Journal Cincinnati 8oc. Nat. Hist., 1902. 

 = Am. Geol., 1903. 



