546 
From the experiments thus far conducted 
upon the determination of sex in plants or 
upon the determination of staminate or 
pistillate members of the flowers, nutrition 
has at least some influence in building up 
the nourishing tissue for the two different 
organs or members. This can in part be 
explained on the ground that antheridia 
and staminate members of the plant are 
more or less short lived in comparison with 
the archegonia and pistillate members, the 
latter requiring more bulk of tissue to serve 
the purpose of protection and nourishment 
to the egg and embryo. It is thus evident 
that while some progress has been made in 
the study of this question we are far from 
a solution of it. Experiment has proceeded 
largely from a single standpoint, viz., that 
of the influence of nutrition. Other factors 
should be taken into consideration, for 
there are evidently other external influ- 
ences and internal forces which play an im- 
portant role, as well as certain correlation 
processes, perhaps connected with the os- 
motie activities of the cell sap. 
The relation of the parts of the flower to 
the foliage leaves is a subject which has 
from time to time called forth discussion. 
That they are but modifications of the foli- 
age leaf, constituents of the leaf concept, is 
the contention of the metamorphosis the- 
ory, and that the so-called sporophylls are 
modified foliage leaves, is accepted with 
little hesitation by nearly all botanists, 
though it would be very difficult, it seems 
to me, for any one to present any very 
strong argument from a phylogenetic stand- 
point in favor of the foliage leaf being the 
primary form in its evolution on the sporo- 
phyte, and that the sporophyll is a modern 
adaptation of the foliage leaf. Numerous 
cases are known of intermediate forms be- 
tween sporophylls and foliage leaves both 
in the Spermatophyta and Pteridophyta. 
These are sometimes regarded as showing 
reversion, or indicating atavism, or in the 
SCIENCE. 
[N.S. Von. VI. No. 145. 
case of some of the ferns as being contracted 
and partially fertile conditions of the foli- 
age leaf. There has been a great deal of 
speculation regarding these interesting ab- 
normal forms, but very little experimenta- 
tion to determine the causes or conditions. 
which govern the processes. 
In 1894 I succeeded in producing a large 
series of these intermediate forms in the 
sensitive fern (Onoclea sensibilis). The ex- 
periments were carried on at the time for 
the especial purpose of determining whether 
in this species the partially developed 
sporophyll could be made to change to 
a foliage leaf and yet possess characters. 
which would identify it as a transformed 
sporophyll. The experiments were carried 
on where there were a large number of the 
fern plants. When the first foliage leaves. 
were about 25 em. high they were cut 
away (about the middle of May). The 
second crop of foliage leaves were also cut 
away when they were about the same 
height during the month of June. During 
July, in which time the uninjured ferns were- 
developing the normal sporophylls, those 
which were experimented upon presented a. 
large series of gradations between the nor- 
mal sporophyll and fully expanded foliage 
leaves. Among these examples there are 
all intermediate stages from sporophylls. 
which show very slight expansions of the 
distal portion of the sporophyll and the dis- 
tal portions of the pinne, until we reach 
forms which it is very difficult to distin- 
guish from the normal foliage leaf. Accom- 
panying these changes are all stages in the 
sterilization of the sporangia (and the for- 
mation of prothalloid growths), on some 
more broadly expanded sporophylls there 
being only faint evidences of the indusia. 
The following year (1895) similar experi- 
ments were carried on with the ostrich fern 
(Onoclea struthiopteris) and similar results. 
were obtained. At the time that these ex- 
periments were conducted I was unaware of 
