82 
of recent events must be impressed with its 
breadth and by the fact that even greater 
specialization is foreshadowed in the near 
future, when the subject of agronomy may 
readily resolve itself into several distinct 
fields of effort. 
The student of farm crops can no longer 
be content with a knowledge of. what .be- 
longs to the art of crop production, but 
must now be well grounded in systematic 
botany, especially in its relation to the bac- 
teria and fungi, and to the plant families 
which embrace the weeds, grasses and the 
common farm crops. He should under- 
stand and follow the work in breeding 
which is being done throughout the world. 
In order to deal with many of the prob- 
lems with which he will be confronted as 
an investigator and which he should be 
able to fully grasp as a teacher, funda- 
mental training in physiological botany 
becomes essential. Indeed, this is only the 
beginning, for the agronomist has not only 
to deal in detail with the plants which con- 
tribute directly to the food supply of man 
‘and of our domestic animals, but also with 
an extensive soil flora almost undreamed of 
a half century ago, upon the study and 
control of which, for the furtherance of 
agriculture, the world is to-day barely en- 
-tering. The agronomist of the future must 
not only deal with the effect of these soil 
plants upon each other and upon the 
higher plants in their parasitical and 
symbiotic relations, but also as producers 
of ammonia and nitrates, and as destroy- 
ers of compounds of sulfur and of nitrogen 
within the soil. 
As suggested by the recent investiga- 
tions of soil amebe by Hall and his eo- 
workers at Rothamsted, he must also deal 
with microscopic animal denizens of the 
soil which may militate against, or, as per- 
haps may yet be found, aid in the growth 
of certain beneficial fungi, and other micro- 
SCIENCE 
[N.S. Vou. XXXV. No. 890 
scopic flora. In fact, the end is not yet, 
for chemistry now plays its réle in furnish- 
ing the agronomist carbon bisulfide, and 
other substances for combating unfavor- 
able animal life in the soil. Chemistry 
also plays its part in controlling and regu- 
lating the chemical reaction, and hence the 
dominance or decadence of various types 
or even of individual representatives of 
the soil’ flora. 
There is reason to believe that we are 
to-day but entering upon the study of the 
organisms and of the conditions best suited 
to ensure. the assimilation of atmospheric 
nitrogen by non-symbiotic means. 
The whole. question of the use of fer- 
tilizers and of their action is daily be- 
coming more complex. It was a simple 
proposition when one supposed that it was 
merely essential to learn what elements 
crops removed from the soil and then to 
supply a proper part thereof, without 
special reference to the particular com- 
pounds used to supply them. To-day, cog- 
nizance must be taken of the effect of the 
associated compounds. The sulfurie acid 
and chlorin combined with ammonia in 
ammonium sulfate and ammonium chlorid 
may have a highly toxic effect from the 
outset, or: such effects may soon develop in 
certain soils if care is not taken to main- 
tain a proper basic condition. The subse- 
quent effect of organic nitrogenous ma- 
nures is quite different on some soils from 
that of nitrate of soda. Even though the 
avoidance of chlorin and sulfuric acid, when 
combined with ammonia, is of vital im- 
portance under certain circumstances, it is 
often less necessary under the same econdi- 
tions if they are in combination with po- 
tassium, calcium and magnesium. For still 
other crops, or on another soil, they may 
nevertheless be used with good effect. 
Another illustration is afforded by ni- 
trate of soda. The residual effect of re- 
