118 BOTANICAL GAZETTE " [aucust 
This is not the place for a review of the literature bearing upon | 
these interesting chemical, physiological, and morphogenetic prob- 
lems, however one wishes to designate them. The views of the three 
botanists just cited are sufficient to show the interest which is being 
taken in these problems. Several writers have contributed to the 
literature. Without any attempt at arrangement for priority or 
extent of investigation, I mention Ewart (1, 2), SOLACOLU (7), TREUB 
(8), Mtirer-Tuureau (5), Nott (6), and Firtine (3). Frttine 
(4) has recently given a review, with a bibliography, of the chief 
literature in connection with an account of his own work on the 
Orchidaceae. From his experimental studies in this family he is 4 
led to the conclusion that the stimuli involved in the ontogeny of a 
the fruit are in part due to an organic substance, not an enzyme, 
external to the pollen grain, in part to the growth of the pollen tubes, 
and finally in part to the development of the fertilized ovules. 
The observations of the authors mentioned above deal chiefly 
with the influence of pollination as a stimulus inducing the develop- 
ment of the ovary up to a stage where the fertilization of the ovules 
is possible, or a little beyond. These phases of the problem are 
much more easily studied experimentally than that of the influence 
of the developing ovule upon the growth of the ovary. The present 
investigation bears upon this point. 
If the developing seed excretes some substance which acts as @ 
stimulus to the development of the ovary wall, or in some other manner 
exerts an influence upon it, it seems not unreasonable to suppose that 
the effect would be greater if several seeds were developing than if 
there were only one or a very few. 
Our problem is essentially this: Does the number of ovules which 
develop to matured seeds influence the size of the fruit, and to what 
extent ? 
In all of the pods which have matured at least one seed, the stimulus 
to development due solely to the penetration of the pollen tube (as 
distinguished from the possible influence of the developing ZY; gote) 
should be the same for all pods, unless the quantity of pollen tubes 
which penetrate the tissue of the style differs from ovary to ovary; 
and the intensity of the stimulus is to some extent proportional bg 
their number. The problem is surrounded by a good many difficul- 
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