No. 464.] STUDIES ON PLANT CELL.— VH. 571 
generally appreciated and the studies on apospory and apogamy 
indicate that much of it is associated with these fundamental 
modifications of the life history (Druery, : 01). 
As to the cause of apospory we are as much in the dark as in 
the case of apogamy. The phenomenon is clearly associated in 
some forms with disturbances in the normal vegetative life of 
the sporophytes. This is particularly true in the cases of mosses 
and Anthoceros and has been suggested for the ferns. Thus 
aposporous developments in Pteris aguilina are from leaves which 
are generally smaller than the normal and whose margins are 
curled so that the leaf often appears somewhat withered and is 
easily recognized at a distance. Bower ('87, p. 322) is inclined 
to regard the phenomenon in the ferns as a sport and does not 
consider that it has deep morphological significance or that it 
offers serious difficulty to the acceptance of the theory of an 
antithetic alternation of generations. 
As we have stated there have been no cytological studies upon 
apospory but there seem to be two possible explanations. That 
which is likely to suggest itself first calls for reduction phenom- 
ena at the time of the aposporous development by which the nuclei 
of the sporophytic tissues may come to contain the gametophyte 
number of chromosomes and are therefore capable of developing 
the sexual generation. But there is another possibility which 
has not yet been considered. We know for several of the sper- 
matophytes (Antennaria, Juel, :00; Thalictrum, Overton, :04; 
Alchemilla, Strasburger, : 04c) that the processes of sporogenesis 
may be suppressed and yet a structure be developed with the 
morphology of the gametophyte generation. Thus the embryo- 
sac will contain the usual number of nuclei grouped in the typ- 
ical manner but these nuclei still have the sporophyte count of 
It seems probable then that the development of 
erference with the nor- 
chromosomes. 
a gametophyte may result through an int 
mal life history and under conditions favorable to the game- 
tophyte even though the nuclei retain the sporophyte number 
of chromosomes. And it is possible that some of the aposporous 
developments in bryophytes and pteridophytes may be of this 
character. It is quite futile at present to carry this speculation 
further. What is desired is some cytological facts. 
