TRANSACTIONS OF SECTION K. 999 
tion with the thallus that bears it. The whole Floridean process, often so com- 
plicated, appears to be an arrangement for effecting the fertilisation of many 
female cells as the result of an original impregnation by a single sperm-cell. 
There is here still a great field for future research; but in the light of our present 
knowledge there seems to be no real parallelism with the formation of a sporophyte 
in the higher plants. 
The gap between the Bryophyta and the Algm remains, unfortunately, a wide 
and deep one, and it is not probable that any Algs at present known to us lie at 
all near the line of descent of the higher Cryptegams. Riccia is often compared 
with Coleochete, but it is by no means evident that Riccia is a specially primitive 
form. In Anthoceros, which bears some marks of an archaic character, the sporo- 
phyte is relatively well developed. To those who do not accept the theory of 
intercalation it is not necessary to assume that the most primitive Bryophyta must 
have the most rudimentary sporophyte. 
Apart from other differences, Bryophyta differ from most green Algze in the 
fact that asexual spores are only found in the generation succeeding fertilisation. 
The spores moreover are themselyes quite different from anything in Alge, and 
- the constancy of their formation in fours among all the higher plants from the 
liverworts upwards, is a fact which requires explanation. I should like to sug- 
gest to some energetic histologist a comparison of the details of spore-formation 
m the lower liverworts and in the various groups of Algz, especially those of the 
green series. It is possible that some light might be thus thrown on the origin of 
tetrad-spore-formation, a subject as to which Professor Farmer has already gained 
some very remarkable results, On Pringsheim’s view some indications of homo- 
logy between bryophytic and algal spore-formation might be expected, and any- 
how the tetrads require some explanation. 
The peculiarities of ths sporophyte in the Archegoniatz, as compared with any 
algal structures, depend, no doubt, on the acquirement of a terrestrial habit, while 
the odphyte by its mode of fertilisation remains ‘ tied down to a semi-aquatic life.’ 1 
Professor Bower's phrase ‘ amphibious alternation ’ expresses this view of the case 
very happily, and indeed his whole account of the rise of the sporophyte is of the 
highest value, even though we may not accept his assumption as to its origin 
de novo. 
I attach special weight to Professor Bower's treatment of this subject, 
because he has shown how the most important of all morphological phenomena 
in plants, namely the alternation of generations in Archegoniatz, may be explained 
as purely adaptive in origin. All Darwinians owe him a debt of gratitude for 
this demonstration, which holds good even if we believe the sporophyte to be the 
modification of a pre-existing body, and not a new formation. 
APOSPORY AND APOGAMY, 
We must remember that the theory of homologous alternation has twice 
received the strongest confirmation of which a scientific hypothesis is susceptible— 
that of verified prediction. In both cases Pringsheim was the happy prophet, 
Convinced on structural grounds of the homology of the two generations in 
mosses, he undertook his experiments on the moss-fruits, in thehope,as he says,” that 
he would succeed in producing protonema from the subdivided seta of the mosses, 
and thus prove the morphological agreement of seta and moss-stem. His experi- 
ment, as everybody knows, was completely succcessful, and resulted in the first 
observed cases of apospory, i.e. the direct outgrowth of the sexual from the asexual 
generation. 
Here he furnished his own verification ; in the second case it has come from 
other hands. In the paper of 1877, so often referred to, he says (p. 391): ‘ Here, 
however [7.e. in the ferns], the act of generation, that is, the formation of sexual 
organs and the origin of an embryo, is undoubtedly bound up with the existence 
of the spore, wntil those future ferns are found which I indicated as conceivable in 
' Bower, Antithetic Alternation. 
* Ges. Abh. II. p. 407. 
