HOOKER ON WELWITSCHIA. 
209 
the genera and even species of Angiosperms, it is a singularly uniform 
one in those of Grymnosperms.” 
But the question still remains. Is the ovular coat of GTymno- 
sperms the equivalent of the ovular integuments of Angiosperms ? 
If not, what is its nature ? And can we indicate its equivalent in any 
other group P Unfortunately, we know almost absolutely nothing of 
the homology of the ovular coat in Angiosperms. And of the little 
which we do know much is derived from teratological evidence which 
requires to rest on a broader basis of data than has as yet been forth¬ 
coming, to be of material value. As shown by Braun^ and Casparyf 
this evidence would appear to favour the foliar nature of the integu¬ 
ments of the ovule in Angiosperms: the nucleus, which these integu¬ 
ments surround and in which the embryo-sac is developed, being an 
entirely new and superadded structure. 
But few cases have been recorded of oolysis, or monstrous ovular 
development, with the care which is demanded to be serviceable in 
the settlement of a question of this kind. Caspary, with Braun’s well- 
digested report upon the nature of the ovular integuments before 
him, describes, with the minutest detail, a case of monstrous white 
clover in which the ovule-coats were found in various stages of de¬ 
gradation from those of the perfect ovules to leaflets of the charac¬ 
teristic trefoil leaf, into which latter the carpel was transformed and 
upon which no trace of the nuclear innovation remained. The nucleus 
was the last to disappear, and remarkably enough, it was found—in 
ovules the inner coat of which had assumed a foliar condition—upon 
the cellular tissue of the leaflets quite removed from the midrib or 
lateral veins. Now, while we cannot safely base an opinion upon 
such and similar cases, we are willing to grant that there is some 
probability attaching to the view of the foliar nature of the ovular 
integument in Angiosperms in many, if not in all cases. In Gym- 
nosperms, on the other hand, at least in Wei wits chia and Gnetum , 
the development, structure and general relations of the ovule-coat 
appear to us to indicate an origin analogous to that of the so-called 
disc in many flowers^ and other axial developments, including the 
calyx or 4 calycuius’ of Loranthacese, Santalacese, and perhaps several 
other Orders. 
We are scarcely prepared at present to enter upon an argument 
in support of this view. A detailed discussion of it would be out of 
place here. We may just observe that no reason occurs to us why 
the integument of the ovule may not differ in its morphological sig¬ 
nification in different groups,—at least in Angio- and Gymnosperms, 
— since we are familiar with a case of substitution of an axial for a 
foliar development in the other parts of the flower. The nature of 
arilloid growths, too, should not be neglected in this inquiry. 
Our space compels brevity upon the internal anatomy and 
* “ Ueber Poly embryonic und Keimung von Caelebogyne” pp. 188-19/. 
f Schrift. d. Physik. Gesell. m Konigsb., Jafirg. ii. p. 65. 
N. H. R.—1863. T 
