152 BOTANICAL GAZETTE |SEPTEMBER 
of the seed and the development of the plantlet to the stage at 
which measurements were made. Since the development of the 
primordial leaves during the germination and establishment of the 
seedling is relatively great, it seemed quite legitimate to use 
the weight of green tissue produced by these leaves as a measure of 
the physiological capacity of seedlings of various types. The fact 
that these leaves are differentiated in the seed, however, constitutes 
a valid objection against their use as a sole measure of the physio- 
logical capacity of the seedling. For such purposes a constant 
based upon some organ developed later seemed desirable. 
In a second study,3 therefore, the tissue weight determinations 
were extended to the trifoliate leaves of the third node, as well as 
to the primordial leaves of the second node. This leaf was used 
because groups of plants of more uniform development can be 
selected at the time of maturity of this leaf, than at any later 
stage, and because the first compound leaf reaches a degree of 
maturity sufficient for the purpose of the present study before the 
primordial leaves are too old to be used. It is possible, therefore, 
to check results by determinations made on organs differentiated 
both in age and in structure. In the first investigation the green 
weight of the leaf tissue served as the fundamental measurement. 
In addition to this character certain measurements on the sap 
properties were also made. In the study of the saps some diffi- 
culties were encountered, and it seemed desirable to discontinue 
that phase of the work temporarily and to carry out determinations 
of dry weight and water content instead. The present study, 
therefore, has to do only with the green weight, the dry weight, and 
the percentage of dry matter. 
Recent investigations fell into two phases. The first was an 
endeavor to determine to what extent seedlings which are morpho- 
logically aberrant in the race to which they belong also differ from 
the normal seedling of the race in their physiological characters, 
in so far as these can be measured by the capacity for the production 
of tissue. In the second the investigation was extended from intra- 
racial to inter-racial comparisons, to ascertain if possible to what 
3 Harris, J. ARTHUR, Further studies on the interrelationship of morphological 
and physiological characters in seedlings of Phaseolus. Brooklyn Bot. Gard. Mem. 
1:167-174. IQI 
