1906] BRIEFER ARTICLES 141 
At the end of the experiment, which lasted seventeen days, the soil 
masses were taken from the baskets and the roots removed from them 
with as little injury to the latter as possible. The fresh roots thus prepared 
are shown in jig. z. The numbers correspond to the culture numbers 
given above. It is at once evident that the root system increases in 
amount throughout the series. Closer observation shows that this is 
due mainly to differences in the relative number and length of secondary 
roots and succeeding branches; the primary roots are of the same number 
Fic. 1.—Roots from a series of wheat cultures grown in Takoma soil untreated 
and in te same with addition of 5000 p.p.m. to 50,000 p.p.m. of stable manure 
in culture 8 as in culture r. They are somewhat longer and more slender 
in culture 8. 
Photographs of single root systems from a similar series are shown 
in figs. 2-5, which bring out the last point more clearly than fig. z. In 
fig. 2, which represents the roots from natural Takoma soil, very few 
branches are to be seen, and these are exceedingly short; practically the 
whole root system consists of the primary roots, with a few adventitious 
roots developed at the extreme base of the stem shortly after germination. 
ig. 3 shows roots from a soil containing 5000 parts per million of manure. 
