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IX. On the Growth and Composition of the Ovarium of Siphonodon celastrineus, Griffith, 
especially/with reference to the subject of its Placentation. By Josera DALTON 
Hooker, Esq., M.D., F.R.S. & L.S. (With a Plate, Tas. XXVI) 
Read June 16th, 1857. 
IN a learned memoir upon some remarkable plants in the Hon. E.I.C.’s Botanic Gardens, 
Calcutta*, Mr. Griffith established the genus Siphonodon upon a very curious Malacca 
tree of doubtful affinity and singular structure, and accompanied his description with 
many observations of the highest interest and importance to the student of structural 
and morphological botany. Amongst these observations is one, which, though published 
for now nearly fifteen years, has never attracted the attention of botanists, owing to the 
limited circulation of the Calcutta Journal, but, which, from its bearing on the subject of 
placentation, has a peculiar interest to myself; for it appears to me to be, if correct, the 
strongest proof hitherto adduced in favour of the theory which regards the placenta as 
terminating the axis, and not as being referable to the carpellary leaf. To this theory my 
own experience is opposed, and as I believed I had proofs of the invalidity of what ap- 
peared to me to be the most cogent arguments previously adduced in favour of it, I more 
particularly wished for an opportunity of testing the accuracy of Griffith’s statement 
with regard to Siphonodon. Mr. Griffith’s conclusion is, * I beg to propose this plant to 
botanists, as an instance in which the placenta is the termination of the axis, bearing 
around its base a verticillus of ovula, and produced upwards into a stigma, a single organ, 
surrounded for the most part by a style with which it has no connexion.” (Joc. cit. p. 255.) 
The foundation for this proposition is Griffith’s conviction that the ovules, of which 
there are many in one horizontal series, are developed on an axis in the centre of the 
flower, independently. of the carpellary leaves, and not enclosed by them or by any other 
organs except the perianth; and that the subsequently developed carpellary leaves form. 
a verticillus externally to the ovules, and rising upwards and inwards, finally enclose 
them. These conclusions appear to me to be founded on erroneous observations, and the 
chief object of the present communication is to lay before the Society my reasons for 
supposing them to be so. 
` I am indebted to my friend Dr. Thomson, who was well-aware of the interest attached 
to this plant, for specimens of Siphonodon flowers preserved in spirits, gathered from the 
same tree, I believe, in the Hon. E.I.C.’s Botanic Gardens, which was described by Griffith. 
These flowers are ih all stages of growth, from buds scarcely perceptible to the naked 
eye, to fully expanded flowers, which measure about 4inch in diameter: I find, how- 
ever (as is usual in flower-buds), that there is little relation between the size of the bud 
and the development of its reproductive organs. In all, I invariably find both whorls of 
the perianth to be fully formed in two closely imbricated series, before any traces of the 
* Calcutta Journal of Natural History, vol. iv. no. xiv. July 1843, p. 231, t. 14. 
