Notes. 
1 66 
the intervention of the vegetative organs. At first sight such appears 
to be the case in the prothalli of the two species described ; sporangia 
were present in close proximity to the sexual organs, the vegetative 
organs of the sporophyte being, at most, represented by a mass 
of cells underlying the group of sporangia, and even this distinction 
may not be recognizable beneath the single sporangia on the edge of 
the prothallus. 
Several reasons may be adduced, however, against regarding these 
phenomena as evidence that the alternation of generations found in 
the Ferns is not antithetic. In the first place, it is to be noted that the 
two forms in which sporangia have been observed upon the game- 
tophyte are highly variable species, and that the varieties studied were 
well-marked crested forms. Further, the conditions under which the 
prothalli existed were in several respects unnatural. Among them 
the fact that fertilization was prevented by not watering the cultures 
from above, and that a prolonged growth of the unfertilized prothalli 
was thereby induced, is of special interest, for it appears that apogamy 
is liable to occur under such conditions in Ferns which, as a rule, 
reproduce sexually. While these considerations do not of themselves 
preclude deductions being made from these peculiar forms of repro- 
duction, they necessitate especial caution in their use in the discussion 
of broad morphological questions. 
Further, a number of reasons exist for considering the production 
of sporangia on the prothallus as a special case of apogamy. In 
Scolopendrium vulgar e a sporophyte may develop from the tip of 
the cylindrical process. This may happen after a group of sporangia 
has been developed. In one case two ramenta were present, one on 
each side of a group of sporangia ; they were in every respect similar 
to the ramenta which develop on the tip of the process when it is 
being transformed into the apex of a bud. Whenever a group of 
very young sporangia was seen it was situated upon the apex of the 
lobe, and the sporangia were in a more advanced stage of develop- 
ment the further the group to which they belonged was removed from 
the apex. This has been most clearly seen in the case of Lastraea 
dilatata , in which no buds with vegetative organs have as yet been 
seen, although in one case ramenta were associated with the sporangia, 
but it also holds for Scolopendrium. The explanation of these facts 
which appears most probable is that each group of sporangia had 
occupied the apex of the process when very young, and had become 
