IMBEDDED SEXUAL CELLS IN THE POLYPODIACEAE 
MARGARET C. FERGUSON 
(WITH PLATES XXVI AND XXVI1) 
About five years ago an assistant in the botanical laboratories 
of Wellesley College, Miss ANN REBECCA TORRENCE, was asked 
to prepare a set of slides, illustrating the development of the sexual 
organs in the ferns, for general class use. In looking over the slides 
which she had marked as valueless, I found several preparations 
showing an unusual origin. of the egg cefis. These slides were 
put aside with the expectation of publishing a note in the near 
future. 
In February 1910, Miss JEAN WINSLow, a student in my 
advanced course in cytology and comparative morphology, was 
puzzled by certain structures which she found in several of her 
preparations. The material was fixed and prepared for study 
by the student herself under the direction of the laboratory assist- 
ant, Miss Emiry P. Locke. Upon examining her slides, I found 
that they contained numerous instances of imbedded antheridia. 
The fern prothallia used for class purposes are grown by the 
gardener. He sows, in clay saucers containing especially pre- 
pared soil, the spores of Péeris and Adiantum, some dishes con- 
taining only spores of Pteris and others containing spores of 
Adiantum. In both instances the structures about to be described 
were taken from cultures marked “‘Pteris,” probably Pieris cristata; 
but since the spores of other species of Pieris are sometimes sown, 
I cannot state definitely the exact species of Pteris which was 
Studied. 
When the imbedded antheridia were discovered, I looked up 
the slides showing the deep-seated origin of eggs in Pteris, and 
we had a very interesting class demonstration and discussion. 
At that time I said to the class that similar phenomena had 
hever before been seen in a leptosporangiate fern; at least, if seen, 
the observations had never been published. Within a week I 
443] [Botanical Gazette, vol. 
