NR MEST ee eT Se 
P j 
De ee 
ON THE SEXUAL ORGANS OF THE CYCADACES,. 65 
Schacht, and especially of Hofmeister, have cleared up the history of 
gymnospermous ovules, their mode of fertilization, and the develop- 
ment of the embryo. The Cycadacee only remain almost completely 
excluded from these investigations; and if this may be accounted for 
by the remoteness of the native country of these plants, and the rare 
occasions of their flowering in our botanic gardens, it is the more to be 
regretted, as their ovules are of the simplest form, and, from their size, 
the best adapted for examination. 
Without treating the subject in detail, I propose to notice and dis- 
cuss the reproductive organs of the Cycadacez. J adopt the morpho- 
logical identity of ordinary leaves with the structures which bear the 
ovules and pollen as the basis of these remarks,—with this physiolo- 
gical distinction between the latter, that in Cycas the male organs, 
collected into a cone, arrest the terminal growth, like the male and fe- 
male organs af all other Cycadacee, so that growth must be continued 
by lateral buds; while the ovule-bearing leaves in the same genus are 
collected into a large terminal tuft, in the centre of which is a leaf- 
bud. We have here the representative of a primitive type ; structure 
and function reach their most simple expression ; the ideal arrangement 
of the organs of reproduction, which has been established in the higher 
plants by the doctrine of metamorphosis, is realized in an actual ex- 
ample. 
In comparing different genera of the Cycadacee with one another, it 
is easy to recognize the homology of the sexual apparatus. From the 
carpophyll of Cycas, which retains in every respect its leafy characters, 
there is a gradual passage, through Dion* and Macrozamia, to the 
squamose and peltate organs of Zamia and other genera. The same 
thing holds good, as I have previously shown at greater length, with 
the male organs. The male and female cones, or the terminal tuft of 
carpophylls, each represent a single male or female flower, composed 
merely of the simplest sexual organs, anthers, and carpe 
While the homologous organs of plants often differ vides, both in 
their anatomical relation and in their external development, a definite 
anatomical resemblance may be traced in the Cycadacee. The carpo- 
* n the habit of quoting Lindley's genus 
Bee farine been Qua opted by error (Miq. Prod. Syst. e p. 22; « Dioon, 
Lindl. Bot. Reg. ubi Dion vocatur" ; DC. oup xvi. 2, p. 537, “ Dioon (errore 
Dion)" ete.) ; but he arii omitted one of the o's, and she opi wrote 
it Dion, and he has elassical authority for fo contracting it 
