ON THE SEXUAL ORGANS OF THE CYCADACER. 99 
and the Gymnosperms, not only fills up, to a certain extent, the gap 
which has hitherto separated the Phanerogams and the Cryptogams (a 
point which has been lately developed by Kirchhoff in a note full of in- 
terest inserted in the * Botanische Zeitung,’ 1867, Nos. 42, 43), but it 
reminds us that it was precisely the vascular Cryptogams and Gym- 
nosperms which, up to the Cretaceous epoch (omitting from conside- 
ration a small number of Monocotyledons), represented the higher 
plants. The passage to the more complicated forms of Phanerogams, 
with hermaphrodite flowers and angiospermous structure, is exhibited 
to us by existing types of Gymnosperms. This is shown in the 
genera Ephedra and Gnetum (the last having two ovular coats) by the 
structure of their stem, by their leaves, and by the rudimentary perigo- 
nial envelopes of the still naked ovules. Welwitschia, the structure of 
which has been so completely made out by the excellent work of 
Hooker, though reminding us of Cycads by the form of its stem, of 
tropical Conifere by its leaves, and of Guetum by its inflorescence, 
makes, on the other hand, the first step towards hermaphroditism (as 
yet unknown amongst the earliest Phanerogams up to the Cretaceous 
period, and perhaps even later) by the development of male organs 
within the same perigonium as a naked ovule. From this point organi- 
zation advances a step in passing to the group of Loranthacea, re- 
garded with the interpretation that Baillon bas attached to it (* Mé- 
moire sur les Loranthacées’). In Welwitschia hermaphroditism is 
still incomplete; in the Loranthacee we find its stage of development 
more advanced Looked at in this way, rudimentary organs appear not 
as atrophied parts, but as the first step towards a more complicated 
plan of organization, which is only realized slowly in the progress of 
ime. 
In agamic generation, individuals are reproduced with all their cha- 
racters; they form, as it were, au indefinite chain of identical ramifica- 
tions, and it is rare for this mode of reproduction to give origin to a 
deviating form.* In sexual generation this constancy of forms aud 
characters is not possible. The two individuals which give origin to a 
* We must not accept this statement without €: if E is ES include 
all cases of agamic reproduction. In Bud variation in plants we have in- 
stances of new forms originating independently of mus 
poseen of aiai ps mu fruits by the Double Almond (Darwin, * Am- 
and P under estication,’ vol. i. p. ), and of nectarine- ers ag 
branches by rint rema, p. 374) are examples.—W. T. D. 
