BRIEFER R ARTICLES. 
NOTE ON THE RELATION BETWEEN GROWTH OF ROOTS 
AND OF TOPS IN WHEAT. 
CONTRIBUTIONS FROM THE HULL BOTANICAL LABORATORY. 
LXXXI 
Srupts in the experimental morphology of plants have dealt mainly 
with the subaerial portions, comparatively little attention having been paid 
to variations in the growth of roots. Thus the literature of the subject is 
very meager. Several authors, especially. MOELLER,’ DETMER,? PERSEKE,3 
Mer,‘ Gat, and FREIDENFELT,® have studied the relation of water to 
the growth of these organs, with the general result that in water itself they 
grow longer and thinner, with fewer branches and root hairs than are 
observed in moist soils. Curiously enough, in soils which are too dry for 
optimum growth, the response is very similar. The roots are long and 
slender and possess few branches excepting near their tips, which lie, of 
course, in moister soil. 
The only observation on the relation of root growth to that of tops, with 
which the writer is acquainted, is that of MoELLER, to the effect that in a 
series of nutrient solutions, of concentrations ranging from 1.0 to 0.05 parts 
per thousand, the actual weight of roots produced varies generally with the 
concentration, but that the ratio of weight of roots to that of tops is much 
larger in the most dilute solution than in any of the others. 
A number of experiments have suggested to the author that the accel- 
fertierns H., Beitrage zur Kenntniss der Verzwergung. Landw. Jahrb. 13: 
167-173. 
2DETMER, ie Ueber den Einfluss dusserer Verhiltnisse auf die Wurzelentwick- 
elung. “ Landw. Versuchst. I5: 107-113. 1872 
3PERSEKE, K., Ueber die Formveranderungen der Wurzel in Erde und Wasser. 
Leipzig. 1877. 
4MerR, E. De Vinfluence des milieux sur la structure des racines. Comptes 
Rend. 88: 1277-1280. 1879. 
Recherches expérimentales sur les conditions de développement des poils 
radicaux. Ibid. 
ep anee de structure et de forme qu’éprouvent les racines 
suivant les sie oti elles végétent. Assoc. Franc. pour l’avance. sc. Compt. rend. 
de la 9° session. Rheims. 1880. 
5GAIN, E., Réle ieilaae de l’eau dans la végétation. Paris. 1895. 
©FREIDENFELT, F., Studien iiber die Wurzeln kraiitiger Pflanzen. I. Ueber 
die Formbildung der Wurzel vom biologischen Gesichtspunkte. Flora 91: 115-208. 
Tg902. 
139] {Botanical Gazette, vol. 4x 
