560 
NATURE 
[JANUARY I5, I914 
The method of photomicrography has been 
applied to the examination of pictures by other 
One example examined was in a private 
artists. 
Fic. 3,—Brushwork of the head of an old man, Sateen a picture in ‘the 
National Gallery known to be by Teniers. 
collection, and it had every appearance of being 
by Teniers. Curiously enough, there appeared in 
it an old man who is to be seen in more than one 
Fic. 4.— Head from a picture des: ribed in a private coilection as by Teniers 
but shown by the brushwork not to possess Teniers’s touch. 
of Teniers’s genuine works. The picture, there- 
fore, had come from Teniers’s studio, as the same 
model was to be found in it, or it was a copy and 
NO. 2307, VOL. 92] 
a forgery. The two photographs reproduced in 
Figs. 3 and 4 show the oldyman as painted by 
Teniers i in the well- known picture in the National 
Gallery of Teniers’s ‘Chateau,’ and the face 
painted in the private picture. The difference of 
brushwork in the modelling of the face is at once 
apparent, while the careless painting oi the beard, 
when compared with Teniers’s, is clearly 
revealed. A. P. Laurig. 
AMERICAN AND GERMAN  INVESTIGA- 
TIONS ON SOIL FERTILITY.1 
HERE is always a refreshing novelty about 
the publications of the American Bureau of 
Soils that makes an irresistible appeal to the 
student of agricultural science on this side of the 
water. We may not always agree with the con- 
clusions reached, and we may sometimes think 
that the facts might be interpreted otherwise, but 
we cannot deny the ingenuity and freshness of the 
work done. 
Of all difficult problems connected with the soil, 
few are more promising than the investigation 
of the remarkable carbon compounds produced 
during the decay of plant residues in the soil, It 
is known in a general way that cellulose and pro- 
tein (two important plant constituents) are broken 
down in the soil to’-ammonia and carbon dioxide, 
but the intermediate products have scarcely been 
investigated in spite of the great biochemical in- 
terest of the process. Dr. Schreiner and his col- 
leagues have recently attempted the problem, and 
their results are set out in a series of bulletins 
issued from the bureau. 
Examination of the soil has shown that numer- 
ous nitrogen compounds can be obtained from it 
as the result of applying certain methods of ex- 
traction; among them are hypoxanthine, xan- 
thine, guanine, ‘adenine, cytosine, as well as the 
split-products of the proteins. There can be little 
doubt that these arise from the decomposition of 
decaying plant residues and other substances 
added as manure. The fact of their existence 
in the soil is of considerable interest, but it is still 
more interesting to inquire whether they serve 
any useful purpose in relation to plant growth. 
The current view is that they decompose to form 
nitrates, which are then absorbed by the plant, 
and built up once more into complex proteins, 
nucleoproteins, &c. Messrs. Schreiner and Skinner 
suggest that some of them at any rate are ab- 
sorbed as such, and utilised direct for the forma- 
tion of protein. One is accustomed to this view 
in animal physiology, but hitherto it has not been 
commonly held among plant physiologists. Ex- 
periments are here described, showing that 
histidine, creatinine, and asparagine caused in- 
creases in green weight in wheat, even when a 
1 ** Nitrogenous Soil Constituents and their bearing on Soil Fertility.” By 
Oswald Schreiner and J. J. Skinner. U.S. Department of Agriculture, 
Bureau of Soils, Bull. No. 87. 
“Occurrence and Nature of Carbonised ser tt in Soils.” By O. 
Schreiner and B. E. Brown. Jé/d. Bull. No. 9 
“Studies in Soil Catalysis.” By M. X. ivan and F. R. Reid. 
Iéid. Bull. No. 86. 
‘*Pflanzenwachstum und Kalkmangel im Boden.” By A. Wieler. 
(Borntriiger, Berlin). Price 14 marks. 
