of Marattia Douglasii, Baker. 3 
Germination of the Spores. 
Fresh leaves with ripe sporangia., as well as prothallia and 
young plants, were collected and were carried back to 
California, reaching there after more than two weeks con- 
finement in a tin collecting-box, in good condition. Spores 
were sown and germinated promptly, but the subsequent 
growth was very slow. No embryos developed from the 
prothallia, but the latter, as well as the young plants, have 
grown perfectly well under bell-jars in the laboratory. As 
the germination of the spores, and the development of the 
prothallium, has already been exhaustively studied by 
Jonkman 1 , my study of these was mainly confined to the 
apical growth of the older prothallium, and certain points in 
regard to the development of the sexual organs. Jonkman 
showed that the prothallium differs mainly from that of the 
leptosporangiate ferns by its more massive character. It 
closely resembles such a liverwort as Pellia , for example, 
having a thick midrib that merges gradually into the thinner 
wings, which, however, unlike most ferns, are more than one 
cell thick, except at the very edge. In artificial cultures the 
growth is very slow, and it may be a year or more before the 
sexual organs are mature. If fecundation does not occur, the 
prothallium seems capable of unlimited growth, and may 
reach a length of two centimetres or more. In the species 
studied by me, the older prothallia were always decidedly 
elongated and not orbicular like those of Angiopteris described 
by Farmer 2 . These old prothallia, like those of Osmunda , 
often develop adventitious shoots (Fig. 4 b ), and in all ways 
give evidence of almost unlimited capacity for independent 
growth. In the older prothallia, the midrib is very massive 
and projects strongly from the lower side where the arche- 
gonia are produced in great numbers. The dark green 
1 Jonkman, La generation sexuee des Marattiacees, Arch. Neerlandaises T. XV ; 
p. 199. 
2 Loc. cit. p. 265. 
B 2 
