28 Brown: APOGAMY IN CAMPTOSORUS RHIZOPHYLLUS 
After the spores had been sown the cultures were placed be- 
fore an east window and the culture solutions were not renewed. 
DEVELOPMENT OF THE PROTHALLIA 
Germination began in about one week after the spores were 
sown and the growth and development of the prothallia were 
rapid at first, then slower as the amount of nutrient solution in 
the capsules decreased. The size and shape of the prothallia 
varied greatly. In the more crowded regions only a few devel- 
oped into more or less heart-shaped prothallia, while the others 
in these regions were ribbon-shaped, irregular or branched. In 
the less crowded regions, especially near the margin of the cultures, 
more developed into heart-shaped prothallia. All the prothallia 
were smaller than when developed in cultures where the nutrient 
solution was renewed from time to time. Many of the prothallia 
showed the great irregularity of margin and the various types of 
marginal outgrowths described by Pickett. Antheridia in large 
numbers developed on the ribbon-shaped and branched prothallia, 
while the heart-shaped prothallia developed meristem which bore 
first antheridia and later archegonia. The latter evidently did 
not function, as no normal sporophytes were formed, although 
large quantities of antherozoids were present. 
In about ten weeks after germination began, an apogamous 
sporophyte was found on one of the larger prothallia near the 
margin of the culture, in one of the less crowded regions. Ina few 
weeks after the apogamous sporophyte developed, the nutrient 
solution in the capsules having been exhausted, new nutrient solu- 
tion was added. The stimulating effect of this new solution could 
soon be noted by the appearance and growth of the prothallia and 
by the development of a few normal sporophytes. However, this 
stimulating influence seemed of short duration, as the culture soon 
began to decline. A number of the prothallia in the more crowded 
regions turned brown and appeared dead, while no more sporo- 
phytes were produced. When the solution was again exhausted 
new was added and again the stimulating influence could be noted, 
but it was not as noticeable as it had been before. The prothallia 
showed increased vigor, although no more sporophytes developed. 
Many of the prothallia which appeared dead gave rise to prolif- 
