424 
NATURE 
| Marcu 4, 1897 
individual, but a growth takes place, and the ovum becomes 
differentiated into two parts—the one sterile, which forms a kind 
of capsule, and the other fertile, which produces numerous spores : 
and as in Nemalion and Batrachospermum (Bower on ‘‘Antithetic- 
Alternation,” iv., 42. of Bot., p. 361): in others the growth 
after fertilisation takes place from an adjoining cell or cells of 
the procarp (Lejolisia, &c.); or, in other cases, from adjoining 
procarps to which the fertilising effect is handed on (Corallina, 
Dudresnaya, &c.), and this results in the formation of corpo- 
spores (Bower, wz supra). Again, in the Pyrenomycetes, the 
result of fertilisation is the production of perithecia, or recept- 
acles which again produce asci or sporangia, which in their turn 
produce spores. 
These modes of generation suggest as their probable explana- 
tion one or other of two different views. The one view is that 
the sexual act is in these cases not reproductive, not the starting- 
point of a new generation—but productive only, and is the 
starting-point of a new organ or growth in the parent plant—so 
that in this view the only mode of reproduction is asexual ; the 
other view, which appears to me the more probable, is that the 
fertilised protoplasm of the ovum is broken up into various 
parts, and that, notwithstanding the intervening stages of de- 
velopment, a portion of it finds its way into each so-called 
spore, so that the spore in all these cases is, in fact, a sexually 
produced cell, and the only mode of reproduction is sexual. 
Perhaps some corroboration of this latter view is to be 
gathered from the cases in which the archegones of mosses 
have shown a tendency to reduplicate the growths which they 
produce. W. Theodor Giimbel (‘‘ Der Vorkeim—Beitrage zur 
Entwichlungsgeschichte der Moospflanze. Nova Acta Acad. 
Cesar.,” vol xxiv. part ii. pp. 578-651) has collected a number 
of such instances. Inthe Polytrichum juntperinum he has found 
an archegone producing two setz and two capsules under one 
calyptra. In Aypum pseudoplumosum he has found two setz 
grown together and bearing two capsules ; in A/zum serratum 
one seta andtwocapsules ; in Bryun argenteum and Splachnum 
vasculosunt one seta with two capsule necks and two capsules. 
These abnormal growths, or some of them, may, perhaps, 
point to a division of the fertilised protoplasm even in the 
archegone ; and they may be only cases of the earlier begin- 
ning of that division which normally takes place after the 
growth of the sporangium. ; 
If this suggestion should be the true one, it would seem to 
follow that fertilisation amongst plants may produce one or other 
of two results: (1) it may directly result in the fertilised ovum 
capable of producing a new plant, or (2) it may indirectly result 
in the formation of a number of cells each capable of reproduc- 
tion ; and to this latter form of reproduction that of the mosses 
should be referred. 
Recurring to the brief summary of the modes of reproduction 
in the Muscinez, it affords room for much observation. We find 
apogamy in almost every form, z.e. we find various modes, all 
of which avoid and exclude the sexual union ; but the economy 
of nature goes much beyond that, and excludes the protonema, 
the gemma, and the leaf-bud. The one thing which is repro- 
duced, whatever else may be omitted, is the cormophyte ; this 
seems to be the one predominant object of nature’s care. 
Moreover, it will be observed that nature is careless whether 
she produces protonema from the one generation or the other ; 
it may arise from the sporangium or the calyptra, which are parts 
of the sporophore, or from the rhizoid stems or leaves, which 
are parts of the oophore. 
It is, moreover, noteworthy from how great a variety of parts 
the new organisms spring—whether in the shape of protonema 
or gemma. It seems as though the whole organism, and not any 
special parts of it only, were teeming with the capacity for re- 
production. 
Ferns.—The normal life-history may be represented thus :— 
( Spore 
@ophore ~ <=.) ees f Archegone 
\ Antherizoid 
| 
= 
Cormophyte 
| 
Sporange 
| 
Spore 
| Prothallus 
SPOLOPUOLe sn eae nee al 
NO. 1427, VOL. 55| 
So that whilst in mosses the cormophyte produces the spore ; 
in the ferns it produces the fertilised ovum ; or, to express it 
in the language of the theory under investigation, in the mosses 
the cormophyte is an oophore ; in the ferns it is a sporophore. 
But side by side with this normal life-history in the ferns, 
we have abbreviated forms to which much attention has lately 
been directed. 
We have cases ot prothallus (capable of producing the two 
sexual forms) arising not from the spore, but from the sporange 
in the Athyrium filix femina, var. clarisstma, and in Poly- 
stichum angulare, var. pulcherrimum ; we have prothallus aris- 
ing from the fronds—from the apex of the pinnule or one of 
its segments, or from the surface of the pinnule in Polystechum 
angulare, var. pulcherrtmum. (Prof. Bower on ‘‘ Apospory,” 
ubé sup., and Druery, Four. Linn. Soc. Bot., vol. xxii. p. 437). 
In Pteris aguzélina growths have been found from the spor- 
angia ‘‘ resembling in some cases moss protonemata, in others 
irregularly shaped prothalli” (Farlow, “‘ Apospory in Pterds 
aqulina, 2 Ann. Bot., 383). 
So, too, in the genus 7yzchomanes we find similar growths of 
prothallus. In 77. pyxzdiferum it grows from the base of the 
sorus ; in 7%. alatwm from the tips of the pinnz of the fronds, 
from the cells of the apices or margins, or from the surface of the 
fronds: and again in the form of flattened strap-like growths 
from the margins or tips of the pinnules in 77. a/azzwm (Bower, 
“Some Normal and Abnormal Developments of the Oophyte 
in Trichomanes, Azz. Bot., 1, 269). Tr. Kazudlfussiz presents 
growths of gemmez and outgrowths on the margins of the fronds 
similar to those of 77. alatum (Bower on ‘‘Apospory and the 
Production of Gemme on 7%, Kaulfassiz,” § Ann. Bot., 465). 
We get other cases in which gemme are produced, and thatin 
a variety of ways; and whereas in mosses the gemmz some- 
times give rise to prothallus and never arise from it, in the ferns 
they seem rather to be produced by the prothallus, and appear 
to produce the cormophyte by direct vegetative growth. They 
have been described as growing in large numbers on the margin 
of the thallus of Vettaria parvila and Monogramme paradoxa ; 
and on the ends of prothalloid growths in 77. alatum. They 
have been observed, too, on 7%. zacéswm and in certain of the 
Hymenophyllee (Bower, 1 Anz. Bot., 273, 283-4). 
But nature goes yet two steps further in this process of short- 
circuiting. In Zy. a/atum the prothallus bears flattened expan- 
sions from which grow buds, which by the ordinary course of 
differentiation produce the leaf-stem and roots of a young cor- 
mophyte (Bower, 1°47. Bot., 287), and the same phenomenon 
has been observed in Lastrea pseudomas, var. cvistata (Druery, 
Jour. Linn. Soc. Bot., xxix. 479-481). j 
Lastly, as in mosses, even the prothallus stage may be squeezed 
out. We get a vegetative bud developed from the base of the 
sorusin Athyrium filix femina, var. elegans, or from the side of 
the sorus in Aspedium (Lastrea) Erythvosorum, var. Monstrum 
vel proliferum (Bower, 2 Linn. Tr.). The growth of such buds 
and small plants arising from them on the pinne of Asplenzum 
bulbiparum, Cystopteris bulbifera and other ferns is a familiar 
sight in our garden houses. 
We have thus a young cormophyte produced by direct growth 
from an old cormophyte—a case of the most simple and short 
reproduction, and I can hardly bring myself to think that repro- 
duction without spore or ovum is justly to be regarded as the 
case of an alternation of generations, one arising from a sexual 
ovum, and the other from an asexual spore with the aid of two: 
principles or facts—apospory, which gets rid of the spore, and 
apogamy, which gets rid of the ovum ; such a mode of regarding 
a simple and direct case of vegetative reproduction seems to me 
to be unreal, and to savour of scholasticism. Apospory and 
apogamy are expressions natural enough if we adopt the doctrine 
of alternation of generations as one which is to be applied to all 
cases of reproduction in the families concerned, because without 
some such epicyclic doctrines the facts will not go into the 
theory ; they are formule for classes of exceptions on the sup- 
posed rule ; but it may be doubted whether the exceptions here 
are not sufficient to destroy the rule. 
If we insist on the view of the two generations, we are struck 
by the confusion which exists between them, for the prothallus, 
which is part of the oophore, may arise either from the spore or 
from the cormophyte, and from the sorus, which are regarded as 
parts of the sporophore ; and the prothallus itself may produce 
either sexual organs, and so an ovum, or it may produce a cormo- 
phyte by direct vegetative growth in the form of a gemma or 
a bulbil, in which case it is difficult to describe it as an oophore. 
