168 BROOKLYN BOTANIC GARDEN’ MEMOIRS 
germination 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 germina- 
tion 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, does, 
however, constitute a valid objection against their use as a measure 
of the physiological capacity of the seedling. For such purposes a 
constant based upon some organ developed later in the life of the 
individual is desirable. 
One of the purposes of this paper is to present the results of deter- 
minations upon a later developed organ. The one chosen is the 
first trifoliate leaf. 
This leaf was used because groups of plants of a higher degree of 
uniformity can be selected at the time of maturity of this leaf than 
at any later stage in the development of the plant, and because the 
first compound leaf reaches a degree of maturity sufficient for the 
purposes of the present study before the primordial leaves are too 
old to be used for a series of determinations. It is, therefore, possible 
to repeat, at a slightly later stage of development of the plant, the 
determinations made on the primordial leaves in the first study as a 
basis of comparison with the work already done and with the series 
of constants to be obtained for the first compound leaves of the same 
plants. 
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 difficulties were encountered, and it seemed 
most desirable to discontinue that phase of the study temporarily 
and to carry out determination of dry weight and water content 
instead. These new measurements have, therefore, been added to 
these for green weight. 
* MATERIALS AND METHODS 
The materials upon which this study is based are the same as 
those previously employed—a mixture of slightly different strains 
of navy beans. The seeds which were germinated in the fall and 
winter months of 1916 were grown in field cultures in 1915. 
Seeds from individual plants were germinated in sand. In sorting, 
the morphologically aberrant seedlings were laid aside with a normal 
plant to serve as a check for each abnormal. An abnormal and a 
control seedling from the same seed plant and germinated in the same 
