PribreR ARTICLES 
APOGAMY IN NEPHRODIUM HERTIPES 
PRELIMINARY NOTE 
Several cultures of Nephrodium hertipes were made beginning 
December 14, 1913. The spores were collected from plants grown in 
the university greenhouse and were sown on sphagnum placed in small 
stender dishes and then saturated with a 0.1 per cent Knop’s solution. 
Before the spores were sown, the dishes containing the medium were 
thoroughly sterilized in an-oven. The prothallia were grown under 
favorable conditions of nutrition, illumination, moisture, and tempera- 
ture. While the sex organs were developing on the prothallia of other 
species under these conditions, it was observed that only an occasional 
prothallium of this fern produced antheridia. Archegonia were never 
seen on any of the prothallia. 
In April 1914, many of the prothallia in the oldest culture were 
typically heart-shaped. A microscopical examination made at this 
time showed that embryos of apogamous origin had begun their devel- 
opment. When the embryo is about to make its appearance, usually 
a small light area, just back of the apical notch, is formed. This appear- 
ance is due to the fact that only a few chromatophores are present in the 
cells of this part of the prothallium as compared with the larger number 
present in the neighboring prothallial cells. Tracheids appear in the 
paler portion of the prothallium just described. The light region grad- 
ually increases in extent. Where the tracheids are formed, a compact 
mass of cells is produced which develops into the apogamous embryo. 
A foot is never formed by the developing embryo. The primary leaf 
first makes its appearance, then the primary root, and later the stem. 
In this order of development of the parts of the embryo, Nephrodium 
hertipes resembles some other apogamous ferns thus far described. In 
some cases, however, the root appears before the leaf. On large, much- 
branched prothallia several apogamous embryos may begin to develop. 
Some of these abort and seldom more than one embryo on a prothallium 
reaches an advanced stage. 
Occasionally cylindrical growths, often containing tracheids, are 
produced from the prothallia. As growth proceeds, these sporophyte- 
like portions flatten out at the growing ends and assume the form of 
Botanical Gazette, vol. 59) [254 
