1910] PACE—FERN PROTHALLIA 57 
The sporophyte structures afforded no opportunity for determin- 
ing whether it contained the haploid or diploid number of chromo- 
somes. YAMANOUCHI found the haploid number of chromosomes in 
apogamous embryos, and concluded that the number of chromosomes 
is not the only factor which determines the characters of the sporophyte 
and gametophyte. STRASBURGER (5) found two kinds of megaspores 
in Marsilea Drummondii, some with the haploid and some with the 
diploid number of chromosomes. It would be expected that those 
with the diploid number of chromosomes would develop sporophytes 
. without fertilization, as the gametophyte, and consequently the egg, 
has the diploid number already present. FARMER and DicBy (1) 
found a vegetative fusion of nuclei in two forms, thus getting the 
sporophytic number of chromosomes without ordinary fertilization. 
The question of apogamy and the literature on the subject will 
not be discussed further at present, as it is hoped the material may 
furnish further evidence of this condition. 
It is a pleasure to express my obligations to Dr. CHaRLEs J. 
CHAMBERLAIN for advice and criticism during this work. 
Summary 
Prothallia kept for three years in the laboratory in as nearly normal 
conditions as possible, except for the absence of liquid water, continue 
to grow, but develop peculiar forms and branching of various types. 
The sex organs continue to develop, antheridia being found occa- 
sionally on the main plant in all positions, but especially on the 
branches. Archegonia become very numerous, approximately 300 
having been found on one gametophyte. These not only develop 
in the apical region, but also far back among the old archegonia. 
Fertilization may take place whenever liquid water is present, 
as shown in several cases where gametophytes were placed in water 
and sectioned later. 
Apogamy is present in a sporangium-like structure which lacked 
the long stalk of the Polypodiaceae, but was not unlike the younger 
stages of the sporangium of the Osmundaceae. It had two layers of 
cells outside the fertile region, the inner of these layers resembling a 
tapetum. 
BAYLOR UNIVERSITY 
Waco, TExas 
