22 



SCIENCE, 



[N. S. Vol. XVJI. JSo. 418. 



and after the roots had attained a length 

 of three or four centimeters he inoculated 

 them with a needle which had been inserted 

 into a tubercle of alfalfa, and placed two 

 of the young plants in a culture jar, which 

 contained a nutrient solution free from 

 combined nitrogen. The peas grew regu- 

 larly so long as they found nourishment 

 in the cotyledons. Then a period of nitro- 

 gen starvation set in, after which the 

 plants recuperated and grew to maturity 

 with the production of fruit. The period 

 of vegetation extended from April 2 to 

 June 10. At the latter date the roots con- 

 tained numerous tubercles. The stalks 

 and roots were separated, dried at 110° C. 

 and weighed. The nitrogen of both por- 

 tions was determined, as was also the 

 weight and nitrogen of two seeds similar 

 to those used in the culture experiments. 

 The following table gives the results : 



The table shows that the plants con- 

 tained ten times as much organic matter 

 and six and six tenths times as much nitro- 

 gen as the seeds from which they were de- 

 rived ; also that the percentage of nitrogen 

 of the roots was greater than that of the 

 aerial portion. Now when it is considered 

 that, in this experiment, there was no 

 nitrogen compound of any kind present, 

 except the infinitesimal quantity intro- 

 duced by puncturing the roots with the 

 needle, and that in two small plants there 

 was a gain of 101 milligrams of combined 

 nitrogen, the claim for the assimilation of 

 free nitrogen must be regarded as estab- 

 lished. 



The order of leguminous plants, there- 

 fore, occupies a unique position in the art 

 of agriculture. The experimental evi- 

 dence herein submitted shows conclusively 

 why leguminous crops have for ages been 

 recognized as being of special value in 

 maintaining soil fertility, and the discus- 

 sion of this subject points to the fact that, 

 in many walks and practices of life, em- 

 piricism has been in advance of science. 

 Henry A. Weber. 



Ohio State Univeesity. 



8GIENTIFI0 BOOKS. 

 Glacial Formations and Drainage Features 

 of the Erie and Ohio Basins. By Frank 

 Leverett. U. S. Geol. Survey, Monograph 

 XLI. Washington. 1902. Pp. 802; 2t) 

 pi. (maps, sections and views from photo- 

 graphs), and 8 figures in the text. $1.75. 

 Ohio is the central area described in this 

 report, and it also includes parts of each of 

 the adjoining states and of the Canadian 

 province of Ontario. The great importance 

 and interest of the glacial history of this 

 region, early studied by Whittlesey, New- 

 berry, Orton, Gilbert and N. H. WinchelL 

 and later by Spencer, I. C. White, Wright, 

 Claypole, Chamberlin, F. B. Taylor and many 

 others, is indicated by about five hundred 

 papers cited in a bibliography of twenty pages. 

 Mr. Leverett enumerates eleven epochs or 

 stages of the glacial period, as follows: (1) 

 The oldest recognized glaciation, called the 

 sub-Aftonian by Chamberlin, perhaps the 

 same as the Albertan of Dawson; (2) the 

 Aftonian interval of recession of the ico 

 sheet; (3) the Kansan stage of glacial read- 

 vance; (4) the second or Yarmouth interval 

 of recession; (5) the Illinoian readvance; (6) 

 the third or Sangamon recession; (7) the 

 lowan readvance, with the principal time of 

 deposition of the loess; (8) the fourth or 

 Peorian recession; (9) the early Wisconsin 

 stage of readvance, with the formation of 

 four successive systems of marginal moraines 

 during the early part of the ensuing reces- 

 sion ; (10) the fifth interval of glacial retreat. 



