Apr., 1921] 
DUNN HISTOLOGY OF GRAIN ROOTS 
209 
being kept as moist as in ordinary greenhouse cultures. At the end of this 
time the shoots were about 15 cm. high, while the roots were about 15 cm. 
long. There was no indication in any of these roots of openings in the 
cortex. The plants grew somewhat less rapidly in the soil and sand cultures 
Fig. I. Transverse section of wheat root, 4 cm. below seed. Plant grown 7 days in 
3-saIt solution. 
Fig. 2. Transverse section of wheat root, 4 cm. below seed. Plant grown 9 days in 
3-salt solution. 
Fig. 3. Transverse section 33^2 cm. below seed of corn root 26 cm. in length. Plant 
grown 8 days in garden soil. 
Fig. 4. Transverse section 3 cm. below seed of corn root 18 cm. in length. Plant grown 
8 da^^s in garden soil. 
En, endodermis; Ep. epidermis. 
than in the solution cultures, but the roots in the sand and soil cultures 
were as long at the end of the experiment as were those in the solutions when 
pronounced openings were noticeable. 
Summarizing all the results so far available for wheat, the openings 
here considered were regularly obtained in roots grown in solution, whether 
the latter were fairly well balanced or decidedly unbalanced and whether 
the plants were grown under winter or summer greenhouse conditions. 
