33 
a pea variety may have. There are factors that determine the 
number of internodes, the length of the internodes (these were 
studied and discovered by Mendel), and whether the plant is 
determinate or indeterminate in its growth. The recessive factor 
for fasciation has a modifying effect by shortening the internodes. 
A recessive factor for yellow foliage in one type discovered as a 
mutant also modifies height, by reducing the length, and even the 
number of internodes in some cases. 
The studies on linkage have resulted in one new linked pair 
being discovered in 1923, with a small percentage of crossing over. 
Yellow foliage G is linked with the ordinary dominant yellow 
cotyledon color, while green foliage is linked with green cotyledon 
color. Crossover individuals of both classes—viz., yellow foliage- 
green cotyledon, and green foliage-yellow cotyledon—have been 
secured. 
Variation in the Boston Fern—Studies of the variation of the 
Boston Fern (Nephrolepis) and other types have been continued 
by Dr. R. C. Benedict, resident investigator. In this connection 
papers have been completed on two interesting groups of variants. 
The first group is comprised among the bud sports of the Boston 
Fern, and includes a most remarkable new form obtained from 
the Pierson establishment at Tarrytown. The leaves of this form 
develop as small dense spheres of indefinitely branching green 
filaments, suggesting moss or liverwort growth rather than fern. 
In addition, these leaves are capable of producing new plants 
directly from the leaf tissue, a feature found in no other one of 
the more than two hundred bud variations of the Boston Fern, 
nor among the wild species of the genus Nephi olepis. 
The second group of variations referred to consists of three 
generations of spore-grown forms raised from the only spore- 
fertile sport in the whole Boston fern series. This group includes 
many distinct new variations and constitutes a new chapter in the 
variation of the Boston fern group. 
Lack of greenhouse space for the cultivation of the very large 
number of distinct varieties already on hand and continuing to 
appear constitutes a serious restriction to the best prosecution of 
the study of these forms. During the winter it is necessary to 
maintain the greater number of the accessioned forms as single 
4 
