1922] CURRENT LITERATURE 407 
apical buds of an intact defoliated stem was compared with the total weight 
of shoots produced from similar stems divided into portions of one node each. 
From the approximate equivalence of these quantities he concluded that 
“the polar character of the regeneration of shoots is due to the fact that all 
the material available for growth reaches the apical and none of the other 
nodes of a long piece of stem.’”’ The relation of this conclusion to LorB’s 
well known earlier work on regeneration in Bryophyllum is not quite clear to 
the reviewer, since nothing appears here concerning the effect of a growth- 
inhibiting hormone by which is to be explained the dominance of the apical 
and the inhibition of the lateral buds. 
Although the reviewer is aware that the two cases are not strictly compar- 
able, it would seem that if inhibition of lateral buds is the effect of a risadcreay 
migrating growth-inhibiting substance, the maximum effect of ‘ 
would result from complete isolation of each bud from the eta Bick 
of its neighbors, as LoEB was able to do in Bryophyllum, and as was impossible 
in REED’s experiments with the pear. Yet the experiment with Bryophylium 
resulted in the production of a greater amount of new growth from the intact 
than from the divided stem 
The arguments in support of the several theories to account for the domi- 
nance of the apical portion of a shoot have been ee —— by CHILp,3 
and several objections to the hypothesis of growth-inh g hormones pointed 
out. It would appear that further progress toward the solution of this problem 
must wait on more adequate information concerning the anatomical relations 
of apical and lateral buds, and of tissue changes in regeneration. For instance, 
the transport efficiency of the vascular supply to the apical as compared with 
lateral buds does not appear to have been adequately investigated. The 
relative age of the terminal as compared with other buds is important in this 
connection. In shoots with the indeterminate growth habit the apical bud 
may establish its dominant réle in the axial gradient, which it thereafter 
retains, in the judgment of CHILD, by virtue of its priority. In shoots of 
limited apical growth different relations may obtain. Again, if inhibition of a 
growing tip is a transmission through protoplasmic connections rather than the 
physical transportation of a substance through the vascular tracts, as CHILD 
holds on the basis of the behavior of simple animals and non-vascular plants, 
evidence of cytoplasmic cell connections should be sought in such active 
portions of the shoot. The effect of callus deposition in the sieve tubes and of 
changes in the phloem (both sieve tubes and parenchyma) toward lignification 
should be determined in relation to a possible gradient in transport efficiency 
from apex to base. The coordination of histological and physiological studies 
in this problem is greatly to be desired.—FREEMAN WEIssS. 
The rapprochement in ecology.—A notable feature in the development of 
ecology has been the marked divergence between the American and Continental 
3 Amer. Jour. Bot. 8: 286-295. 1921. 
