27 



Table VII. — continued. 



Plants. 



iV'itrogen, gram 3. 



In Si!0(l, 



or Plants ; 



and 



Manuro, 



if any. 



Tn 



Products. 



Gain 



or 

 Loss. 



Nitrogen 



in 

 Product.s 



to I 

 Supplied. 



1851, '52, '53, a7id '54;: Prej^ctred soil, or pumice ivith ashes ; distilled 

 water, free air, under glazed case.* 



Haricot (dwarf), 1851. 



Haricot, 1852 



Haricot, 1853 



Haricot ( ' 

 Lupin (w ' 



Lupin, I80 1 



Lupin, 1851 



Gars, 1852 



VV'lieat, 1853 



Garden Cress, 185 1. 



), 185A. ... 

 1853 .... 



-0.3 19 

 0213 

 0293 

 -0318 

 0214 

 0109 

 -OSfi? 

 0031 

 -OOfi l 

 -0259 



-0380 

 0-0238 

 0-0270 

 -0350 

 0256 

 -0229 

 -0387 

 0-00 it 

 -0075 

 0272 



+ 0-0031 

 + 0025 

 -0-0023 

 + 0-0032 

 + 0-0042 

 + 0030 

 + 0-0020 

 + 0-0010 

 + 0-0011 

 + 0.0013 



•09 

 -12 

 •92 

 -10 

 -20 

 -15 

 •05 

 •32 

 •17 

 •05 



1858 : Nitrate of Potassium as Ma^mre.f 



Heliantlius 



1 



0^01 11 J 

 -025 j; 



0130 

 0-0245 



-0-0014 

 ■ 0^0010 



0^90 

 96 



The last two columns of the table (VII) show the actual and pro- 

 portional gain or loss of nitrogen in M. Boussingault's experiments. 

 It will be seen that in his earlier experiments, those in free air in a 

 summer house, the leguminous plants, trefoil and peas, did indicate a 

 notable gain of nitrogen: but, in all his subsequent experiments, there 

 was generally either a slight loss, or, if a gain, it was represented in only 

 fractions, or low units, of milligrams. After 20 years of varied and 

 laborious investigation of the subject, M. Boussingault concluded that 

 plants have not the power of assimilating the free nitrogen of the atmo- 

 sphere. And in a letter received from him as recently as 1876, after 

 discussing several aspects of the question, he says : — 



" If there is one fact perfectly demonstrated in physiology, it is 

 this of the non-assimilation of free nitrogen by plants ; and I may 

 add by plants of an inferior order, such as my^oderms and mush- 

 rooms." — (Translation.) 



Our own experiments on this sub'oct were commenced in 1857, 

 and a young American chemist, the late Dr. Pugh, of the Pennsylvania 



* Ann. Ch. Phys., S6r. [3], xliii. (1855). 

 t Compt. rend., xlvii. (1858). 

 X Nitrogen in Seed and Nitrate. 



