147 
first leaves, and this plant is soon as full of flowers and fruit as if 
its entire growth had taken place in a soil of excellent quality. The 
crop 1s inen very good. It contains a large quantity of nitrogen, 
which evidently could only come to it from the atmosphere. 
This recrudescence of vegetation shows itself at a time when the 
weight of the plant is eight or ten times that of the seed, and similar 
contrasts are often observed in two stalks grown in the same pot, 
which are, therefore, consequently in the same soil, under the same 
conditions, the seeds being as similar as possible. 
In a word, the experiments of Ville teach us two unforeseen and 
equally remarkable facts. The first and most important is that 
leguminous plant can live and prosper in a soil entirely destitute of 
all nitrogenous compounds, thus necessitating the direct assistance of 
the atmosphere : the second is that all seeds of the same kind are 
far from behaving in the same manner, whence it results that the 
course of the experiment is eminently uncertain. 
With plants of the family of the Graminee nothing similar takes 
place. The results are absolutely invariable; the crop is zero if 
the soil does not contain nitrogenous substances. It increases regu- 
larly with the quantity of fertilizer, and each seed produces about 
the same weight of dry material. 
The irregularity of the results given by the leguminose under the 
same conditions shows that there could be in this case no question 
as to the accidental gains of nitrogen, attributable to ammonia or 
to atmospheric dusts, or to the w ater used in watering; the fact had 
been discovered, but its true cause had escaped the discoverer. 
G. Ville, convinced of the correctness of the positive results ob- 
tained by him, was certainly right in concluding from them that cer- 
tain kinds of plants attract arbonic-acic gas, but he was not master 
of his experiment. Other observers also tried to repeat it after him, 
but did not succeed. Boussingault, in particular, having placed his 
plants in spaces that were too restricted to allow of the free dev elop- 
ment of their roots, only obtained stunted plants weighing scarcely 
four or five times as much as the seed and containing no more nitro- 
gen than the latter, because they had never attained the second stage 
of their growth. 
In consequence Boussingault, who, however, had several years be- 
fore obtained results similar to those of Ville, thought himself justi- 
fied in laying down as a principle that vegetables, no matter to what 
variety they “belong , are always ine apable ‘of taking even the smallest 
quantity of nitrogen from the air. 
I shall not dwell upon this discussion, which has remained cele- 
brated and which is very much to be regretted, inasmuch as the re- 
sult of it was that by deterring those students who would have liked 
to pursue the study of the question further its definitive solution was 
retarded for thirty years. I only. wish here to confine myself to a 
emer point in it, which i is that the fixing of free nitrogen by plants 
ras observed already in 1850, with all the characteristics of irregu- 
levity belonging to it and as they have been again described in 
recent physiological researches of German phy siologists. 
I now come to the recent works, and © shall commence by those of 
Berthelot, in which we shall be confronted by an entirely new idea— 
that of the interrelation of microscopic life and the phenomena of 
vegetable nutrition. 
