488 SLosson: THE ORIGIN OF 
sent out branches and it appeared extremely probable that on the 
branches the organs that had been removed were often regener- 
ated. Each of the branches was shaped more or less like a 
complete prothallus, and many produced plants of pure ae 
borne, as in the normal prothalli, close to a sinus. I did ne 
wish to disturb the cultures sufficiently to make certain, but tt 
is not probable that all, if any, of these plants were the result 
of asexual growth; (2) Very many of the antheridial sections, — 
though possessing roots when planted, either died immediately or 
appeared to fade and remain faded for weeks, reviving only by 
sending out branches. The archegonial sections, on the contrary, 
though rootless when planted, as a rule quickly produced roots 
and grew rapidly. 
Since there appears to be no way of dividing prothalli that 
offers any certainty that the organs cut away will not be regenel- 
ated, it is evident that in attempting to cross species of ferns that 
method of dividing and bringing prothalli together is best in base 
the prothalli offer most quickly facilities for cross-fertilization, 
order that it may take place before regeneration of the organs. As 
antheridial sections that die or fade cannot be said to offer such 
facilities, in the experiments described further on whole prothall 
have been substituted for the antheridial sections. In cutting the | 
archegonial sections the incision has been made transversely close 
to the sinus of each prothallus in order to make certain of er 
ing archegonia only on the archegonial sections. Then, oe 
ing the section containing antheridia, the archegonial section ) : 
prothallus of one species has been planted against a whole pro 
SP SP YY 
x nts = 4; 
Fic. 1. X 4. The letters in the series uniformly refer to the same pia 
‘ des Be Dd, 
Asplenium platyneuron ; B, hybrid artificially produced ; C, Asplenium ebenot 
Camplosorus rhizophyllus. 
halli 
thallus of the other species with the lower surfaces of the pr ee 
pressed close together, in the hope that when gntherori Be 
be set free on the whole prothallus some would reach an 
