254 Notes. 
gonial projections. In the place of the projection nearest to the 
apex a vegetative bud arose. 
It is possible to draw some general conclusions from this series of 
cultures. It is a striking fact that in every one of the species, 
prothalli, which under normal conditions would have produced 
normal embryos, became, after a longer or shorter period, apo- 
gamous. Further, there was a general similarity in the changes of 
form and structure of the prothallus, which preceded this result. 
This form of apogamy, occurring after prolonged cultivation of 
normal prothalli under special conditions, may be distinguished as 
induced apogamy , in contradistinction to direct apogamy , by which is 
meant the immediate production of vegetative buds by prothalli, 
which are usually incapable of being fertilized. Both forms occur in 
Nephrodium Filix-mas. 
The causes which appeared to induce apogamy in these prothalli 
were the prevention of contact with fluid water which rendered 
fertilization impossible, and the exposure to direct sunlight. Possibly 
the temperature also had some effect. The case of Nephrodium 
Filix-mas shows that the variable condition of the sporophyte, as 
indicated by cresting, &c., though possibly predisposing to the 
changes which lead to apogamy, does not stand in any necessary 
connexion with the phenomenon. 
That different degrees of apogamy are distinguishable was also 
shown by these cultures. The cylindrical process, arising from the 
apex of the prothallus, or from its under-surface, is to be regarded 
simply as a modification in form and structure of the gametophyte 
dependent on the altered conditions, and possibly a direct adapta- 
tion to these. The next stage is seen in cylindrical processes, 
which, while bearing sexual organs, also produce isolated members 
of a sporophyte (roots, ramenta, sporangia). It is to be borne in 
mind, however, that tissue differing from the rest of the process 
always occurred beneath the last-named structures. The final stage 
is the production of a vegetative bud capable of further growth as a 
typical sporophyte. In this a series leading from the bud arising 
by transformation of the tip of a cylindrical process, to buds pro- 
duced on or in the place of archegonial projections, and from this to 
buds situated on the under-surface of the prothallus itself, can be 
recognized. 
The readiness with which the intermediate form between gameto- 
