236 Boodle . — On the Production of Dwarf Male 
cultures were spoilt by Bacteria. In cultures made in watch-glasses, the 
spores and prothalli generally remained healthy for a long time. Bacteria 
sometimes appeared where a number of spores were crowded together, and 
the germination of these spores was thus prevented or checked ; but, where 
the spores were more scattered, Bacteria were seldom to be seen. It should 
also be mentioned that a fungus, which Mr. G. Massee, F.L.S., kindly named 
for me as Dendryphium effusum , Bon., was sometimes found growing on 
the wall of the sporangium, both in cultures and on the living plants, but 
the presence or absence of the fungus appeared to have no effect on the 
germination of the spores in the sporangium. 
Figs. 1 5-20 are given to show the characters or peculiarities of some 
young stages of prothalli. Figs. 1 5 and 16 are two prothalli of T. hymeno- 
phylloides at the three- celled stage, showing different arrangement of the 
cells, Fig. 15 being from a culture of spores in water in the dark, Fig. 16 
from a sporangium in light. Fig. 17 is a more advanced prothallus of the 
same species from a spore grown in water in the light. Figs. 18-20 are 
prothalli of T. Fraseri , Fig. 19 being from a culture of spores on blotting- 
paper in darkness after thirty-three days. The cell marked with a cross 
contained very little chlorophyll. In cultures in the dark it was often 
noticed that the last-formed cell had scanty chlorophyll-grains, i. e. when 
the prothallus had reached a five- or six-celled stage. Under the condi- 
tions of the experiments it is probable that, at this stage, growth had 
nearly ceased, light being necessary for further development. Fig. 18 is 
a prothallus grown on blotting-paper in the dark. The primary rhizoid-cell 
has not been formed, but a secondary rudimentary rhizoid is present. 
Fig. 20 is a prothallus from a similar culture to the last, and shows an 
unusual form with transverse growth. 
In the germination of the spores of Todea Fraseri and T. hymenophyll - 
oides, there is some diversity in the arrangement of the cells of the young 
prothallus, but the commoner types agree well with the same stages in 
Osmunda cinnamomea and O. claytoniana as figured by Campbell, and 
Todea barbara as figured by Luerssen. Thus Figs. 14, 16, and 19 on 
PL XVI correspond with Campbell’s Figs. 12 <2, 5 and 14 (’ 92 , PI. Ill), 
and Luerssen’s Figs. 6, 13, and 19 (’ 74 , PL XXIII). In rather later stages 
also the prothalli of the filmy species of Todea , while showing variation in 
breadth, & c., reproduced several of the forms figured by Campbell and 
Luerssen in Osmunda and Todea , including occasional examples showing an 
early forking of the prothallus. 
We may now return to a consideration of the results of the experiments. 
Free spores germinate normally, and produce prothalli of considerable 
size without forming antheridia L Hence the production of dwarf male 
1 At the conclusion of the experiments the largest prothalli consisted of more than twenty cells, 
but no antheridia had been formed. 
