Studies in Growth. IV. Correlations in Development. 
BY 
W. H. PEARSALL. 
With six Figures in the Text. 
T HE earlier papers of this series ( 1 , 2 ) dealt with certain aspects of the 
growth of yeast and of roots upon cuttings. As a result of the con¬ 
clusions drawn from those special cases, it appeared to be possible to 
Fig. i. Rate of growth of bean roots in volume. R indicates appearance of secondary roots; 
stem removed at s; new shoots appear at N. 
explain some of the earlier data obtained in these studies, which had until 
recently seemed to be of little value. 
The first measurements undertaken in this connexion were those of the 
volumes of roots grown from Broad Beans (Vicia Faba^ L.), the root volumes 
being measured in a volumometer as previously described (8). In the first 
series of observations, begun on July 31, 1920, the beans were grown 
in Shive’s optimum three-salt culture solution ( 9 ), this being renewed every 
two days. The volumometers were kept in a water-bath, at an approxi¬ 
mately constant temperature of 15 0 C. ( + i°). The water-bath was covered 
so that the roots were in the dark. The whole apparatus was set up in an 
artificially warmed greenhouse. 
[Annals of Botany, Vol. XXXVII. No. CXLVI. April, 1923.] 
