1894. ] Anatomical and Physiological Researches. 287 
Frank claims that the results reported by Liebscher!® with 
‘mustard are in general confirmatory of his experiments. This 
latter investigator worked under field conditions and claims 
that upon rich soil white mustard can collect twice as much 
nitrogen as thrifty peas, beans or clover. Liebscher’s paper 
is very full and explicit as to methods and details but his ex- 
periments were conducted under such conditions that the dif- 
ferent factors were not controlled, hence the value of the con- 
clusions is much lessened. He concludes that the ability of 
under optimum conditions. In rich unsterilized soil, peas do 
not increase in thriftiness even if they are fed with combined 
nitrogen, while the non-leguminous plants are much benefited 
by such a treatment. 
Liebscher thinks that errors of analysis will hardly explain 
_ the quantity of nitrogen apparently collected by the oats and 
mustard but as he admits,no control was exercised over the 
rainfall or the water used for watering, neither was the in- 
fluence of algz or soil organisms taken into consideration. | 
It would seem that while there may be an increase in the 
nitrogen under field conditions that may possibly possess some 
economic value, vet from the standpoint of physiology, these 
experiments are not sufficiently conclusive to prove that the 
higher plants themselves were able to fix the nitrogen. 
Lotsy!! has recently studied this question relative to the 
mustard assimilation in a careful way, employing both sand 
and water cultures in sterile and unsterilized condition, and 
from his work concludes that neither S. a/éa nor S. nigra are 
able to live without combined nitrogen. In this connection 
it ts only necessary to refer to the exceedingly careful re- 
Searches made previous to this by Schloesing (fils) and agent 
rent!? in which they showed by a comparative set of experi- 
ments, by both direct and indirect methods of analysis, that 
white Mustard, oats, cress, and spergula were unable to as- 
Similate free nitrogen. ‘ 
In 1890 Petermann!? affirmed that barley was as efficient a 
nitrogen collector as beans. Since then he has published a 
“cond paper’ giving full details of his experiments. His 
‘° Journ. f, Landw. 41- 180, 1893. ea Aare eee 
- ES. Dept. of Agricuiture 78. 
| 
| 
| 
1? Ann, Inst Past. 6: 
12 Mém pie - Seas oe 
14 : - Toy. de Belg. 44: 1889. 
Mém. Acad. roy. de Belg. 47: 1892.-Abs. in Chem. Cent. 2: 988. 1893. 
a2—Vol, XIX— No. 9. 
