LEAF- TISSUE PRODUCTION AND WATER CONTENT IN 
A MUTANT RACE OF PHASEOLUS VULGARIS 
J. ARTHUR HARRIS 
Introductory 
Ina specading paper’ it was shown that the survival of the bean 
plant is in a measurable degree dependent upon the morphological 
characteristics of the seedling. In 1915 a series of investigations 
was undertaken to determine, if possible, something of the proximate 
causes of the differential death rate. It was also hoped that some 
light would thereby be thrown upon the proximate causes under- 
lying the occurrence of teratological variations in the seedlings of 
Phaseolus. In undertaking this work the assumption seemed 
justified that if innate physiological conditions which might affect , 
growth be associated with morphological variations, some influence 
of these factors should be recorded in the size or other characteristics 
which result from the relatively enormous expansion which the 
organs of the embryo undergo in the course of germination and the 
establishment of the seedling. 
A first study? demonstrated. that ‘tatoos seedlings in 
general show a lower capacity for the development of primordial 
leaf tissue than do normal seedlings grown under as nearly as pos- 
sible identical conditions. The data then available indicated that 
a reduction of the volume of primordial leaf tissue is associated 
with abnormalities of all the abnormal types studied, but that the 
type of variation influences in some degree the amount of reduction. 
In these first experiments the conclusions were based on primordial 
leaves only. The use of such leaves has the obvious disadvantage 
that they are formed in the seed, and undergo merely an enormous 
expansion (and possibly a little differentiation) in the germination. 
* Harris, J. AntHuR, A simple demonstration of the action of natural selection. 
Science, N.S. 36:713-715. 1912. 
eS 
7. Studies on the ter 
The development of the peace leaves in Ca bean seedlings. Genetics 
1:185-196, 1 
151] [Botanical Gazette, vol. 72 
