No. 464.) STUDIES ON PLANT CELL.— VII. 569 
prothallus can so readily take on sporophytic potentialities and 
the sporophyte develop gametophytes vegetatively. But Lang 
recognized that the importance of this evidence would be mini- 
mized should it be found to depend on changes of nuclear struc- 
ture. These nuclear changes have been established at least for 
apogamy, either in the suppression of the reduction phenomena 
of sporogenesis or by the substitution of asexual nuclear fusions 
for the sexual act, and the argument for antithetic alternation 
of generations seems to the writer stronger to-day than ever 
before. 
6. APOSPORY. 
Apospory is the suppression of all processes of sporogenesis 
and the development of a gametophyte generation directly from 
the sporophyte. The term was first proposed by Vines (Jour. 
of Bot., 1878, p. 355) in a discussion of the life history of Chara 
and adopted by Bower ('86, '87) in a general treatment of the 
subject based on Druery's (86a, ’86b) discoveries of prothalli 
developed in place of sporangia directly upon the leaves of 
Athyrium filix-femina and its variety clarissima. The phe- 
nomenon of apospory is best known among the ferns where it 
has been most extensively studied but so far no cytological inves- 
tigations have been published. Since apospory results in the 
development of a gametophyte generation (presumably with the 
gametophyte number of chromosomes) without the preliminary 
process of sporogenesis it becomes a very interesting problem to 
know just how this reduction of the chromosomes is effected. 
Apospory is probably not uncommon in the mosses and has 
also been reported for the liverwort Anthoceros. The inde- 
pendent studies of Pringsheim (76) and Stahl (76) established 
the facts that pieces of the sporophyte stalk (seta) of Hypnum, 
Amblystegium, Bryum, and Ceratodon when placed on damp 
soil developed a protonema which in its turn produced leafy moss 
Stahl also found in Ceratodon that protonemata 
he capsule wall and Brizi ('92) discovered a 
nt from the atrophied capsule of Funaria 
’99a, p. 421) has confirmed the conclu- 
gametophytes. 
may arise from t 
similar developme 
hygrometrica. Correns ( 
