368 Bower. — On antithetic as distinct from 
and apospory 1 : it will be unnecessary to describe these pecu- 
liarities afresh, but a word must be said as to the application 
of the terms. In the strict sense of the terms (that, in fact, in 
which they were first applied), these phenomena consist in the 
direct vegetative transition from one generation to the other 
in cases where antithetic alternation is present, and I think it is 
desirable to maintain them in this sense. The more pro- 
miscuous use of them among those Thallophytes in which 
a true antithetic alternation does not occur will only lead to 
confusion 2 , even though the phenomena so described may be 
more or less analogous to the true type. 
The mere fact that apogamy and apospory may occur, 
will suggest that the distinction between the two antithetic 
generations is not so clear a one as that indicated above : and 
some will be disposed, like Pringsheim, to conclude, from 
observations of apospory, that since the direct vegetative 
transition from the one generation to the other has been 
demonstrated in certain individuals, their distinctness of 
phylogenetic origin cannot be maintained. But against 
this conclusion is to be placed the fact that both apogamy 
and apospory are decidedly rare phenomena ; that they 
appear for the most part in plants of variable species, and, 
in the case of apogamy at least, under conditions of culti- 
vation which are not those natural to the plants. Moreover, 
attempts to induce apospory, though successful in certain 
Mosses, have been entirely without result in Ferns 3 . These 
facts, taken together with the results of comparison of the 
Archegoniatae, which point clearly to the view that the sporo- 
phyte originated by interpolation, lead me to conclude that 
these are phenomena of a teratological nature, and are not to 
be taken as evidence with regard to the evolutionary relations 
of the sporophyte and the gametophyte. 
Finally, if such a view of the origin and true meaning of 
antithetic alternation as that above put forward be accepted, 
1 Linn. Trans., vol. ii. part 14, 1887, p. 302. 
2 Compare MacNab, Proc. Roy. Dub. Soc., n. s., vol. iv. pp. 466, &c. 
3 Annals of Botany, vol. iv. p. 168. 
