320 PROF. F. О. BOWER ON APOSPORY AND ALLIED PHENOMENA. 
the normal cycle may be passed over, and accordingly a short cut may be made from one 
point directly to another. Two such cases of excision are now recognized—that which is 
termed apogamy, where there is direct transition from oophore to sporophore without 
sexual process; and apospory, where there is direct transition from sporophore to oophore 
without spores; these may respectively be represented to the eye as in the fig. 1, which 
further distinguishes those cases where the oophore originates from the sorus (Type пә; 
from those where it originates from the ordinary vegetative portion of frond (Туре 1.). 
In seeking among the higher plants for cases comparable with these of apospory in the 
Mosses and Ferns, we must be prepared to find the phenomena less obvious, since in them the 
oophore becomes suppressed, and the sporal and sexual process of propagation more nearly 
identical іп time and space. І am,not aware of any recorded case of true apospory in either 
the higher heterosporous Pteridophyta or in the Phanerogams ; still there are, in those 
cases of adventitious embryos observed by Strasburger*, sufficient points of similarity to 
warrant a comparison being drawn. Не found in Рима ovata, and in JVothoscor- 
dum fragrans, that a budding of the cells forming the single remaining layer of the 
apex of the nucellus results in the formation of numerous embryos in the single ovule, 
but it was left undecided whether or not fertilization is necessary, though the entry of the 
pollen-tube into the micropyle of the ovule seems usually to precede the formation of 
the adventitious embryos. Again, in the notorious case of Celebogyne, adventitious 
embryos are formed in a similar way, but without fertilization. Now if the cells which 
thus give rise to the embryos be regarded as ova (which is hardly a possible view, considering 
their origin, the fact that they are not fertilized, and the continued presence of a cell- 
wall, &c.), then such cases might be compared with those of the aposporous Ferns, since 
they would be examples of production of the ova more or less directly from the sporophore ; 
this would, however, be a somewhat strained interpretation, and it seems more reasonable 
to regard these adventitious embryos rather as peculiar examples of sporophoric budding, 
associated more or less closely with a process of fertilization in Funkia and Nothoscordum | 
but independent of it in the case of Celebogyne. Itis to be noted that these adventitious 
growths follow a certain arrest of function in the embryo-sac itself; the true ovum does 
not appear to be functional in these plants, and accordingly the appearance of the adven- 
titious embryos may be regarded as a correlative or substitutionary growth +. 
Lastly, it remains to discuss the case of Chara, to which, it will be remembered, the 
term “ aposporous " was first applied by Vines t; he made the ingenious suggestion that 
in the life-history of Chara there is to be traced a true alternation of generations; 
that the proembryo is to be regarded as the sporophore, which, however, does not pro- 
duce spores, but by a process of aposporous budding the oophore is produced by direct 
vegetative growth from the sporophore; in fact, he suggests that the condition which 
can be artificially induced in the Mosses is the normal and constant condition in Chara. 
It must be admitted on all hands that this is a pure hypothesis; beyond the fact that 
* Befruchtung, p. 63, plates vi., vii. 
+ The case of Disciphania described by Ernst (* Nature, Oct. 7, 1886) may be mentioned here, though it is not 
yet clear whether it be a true case of parthenogenesis or of врогорһогіс budding. 
$ Journ. of Botany, 1878, р. 355. 
