412 BOTANICAL GAZETTE [MAY 
6. OTHER HYPOTHESES 
The foregoing hypotheses have seemed the most reasonable ones 
to explain the relationship between the length of the fruit and the 
number of seeds developing, without the assumption of a direct 
causal relationship between them. All have given negative results 
in the sense that they have failed to show any reason for the inter- 
relationship between length and number of seeds external to the 
two characters themselves. This does not prove that there is a 
direct causal relationship between them, that is, that their inter- 
dependence is not due to some outside influence, but I think that 
the factors suggested are the most important ones, and I have no 
data for taking up others on the present material. 
We may conclude, therefore, with reasonable confidence, that 
the developing seed does in some way exert a developmental 
stimulus on the ovary wall. The nature of this stimulus must be 
ascertained by further studies. 
V. Recapitulation 
The chief problems, methods of reasoning, and conclusions from 
observations detailed both above and in an earlier paper on Cercis, 
may be briefly reviewed here. 
That pollination is in many cases a stimulus to the development 
of the ovary now seems fairly well established. Several biologists 
have suggested that the developing seed also exerts an influence 
upon the growth of the fruit. 
The establishment of this second hypothesis Sees far greater 
difficulties than that of the first. So far as I am aware, no one 
has isolated bodies from the growing seed which when introduced 
into other ovaries accelerates development. Nor has it been 
proved that young ovaries with larger numbers of developing seeds 
show a higher rate of growth; and even if this were demonstrated, 
it would be impossible to say that the acceleration of growth was 
not due to the stimulation of an unusually large number of pollen 
tubes. 
The most feasible method for a preliminary study seems to be 
to work with mature fruits and to ascertain whether the number 
of seeds may have had an influence in determining the size of the 
