CONTRIBUTIONS TO BOTANY. 
41 
naked, or at least, their only covering is reduced to a thin mem- 
brane, which in the dried state remains more or less attached to 
the inner surface of the putamen. The phsenomenon of the deve- 
lopment of these, which I have proposed to call exutive seeds (see 
last note), has been frequently observed by many eminent physio- 
logical botanists, more particularly by Mirbel, Schleiden, Meyen, 
Decaisne, and Griffith. The latter has shown, that among the 
changes that take place in these cases, is the constant prolonga- 
tion of the erabryonary sac, outside of the ''nucleus*,” or body 
of the ovule, and that it is curious to witness the rapidity with 
w'hich this exsertcd portion grow's, and here becomes filled wuth 
albuminous tissue : another result being the incorporation of the 
remaining portion of the sac with that tissue. A similar pro- 
longation of the embryo-sac was also noticed by the same accu- 
rate observer in Avicennia-\, and he infers that this phsenomenon 
has only been remarked in cases associated with a particular form 
of free central placenta J •, but this is not correct, for we have 
evidence, that its occurrence is not constant among the Ciono- 
spermcE. We know likewise, from the observations of Mr. Griffith 
himself, that the same occurs in Congea, Loranthus, &c. Dr. Plan- 
chon also has minutely described a similar phsenomenon in the 
seeds of Veronica^, where the embryo is formed wfithout the 
usual integuments, and remains covered merely by its embryo- 
sac, that protrudes outside the main body of the ovule, improperly 
called the " nucleus,” and which afterwards shrivels into the form 
of a secondary funicular cord : in these instances the embryonar}" 
sac becomes thickened, and assumes the appearance of a peri- 
spermal covering around the albumen of the seed, very different 
in its origin from the true testa of indutive seeds. 
M'e may infer that nearly the same changes take place in the 
development of the seed in Olacacea that Mr. Griffith has so 
minutely observed in Santalum and Osyris ; for in the ripe fruit 
of Liriosma, examined in the di-ied state, independently of the 
thickened and lengthened cionosperm, which is pressed into a 
deep longitudinal groove, formed by its pressure, in one side of 
* This term, though generally used in this case by botanists, is manifestly 
incorrect, and has been employed only because it is applied to the identical 
body which is enclosed uithin its several tunics in ordinary seeds ; it leads 
to misconception, because it is difficult to imagine the “ nucleus ” can mean 
the external covering of the ovule, while the protruding real nucleary body 
becomes the entire seed. It would be more conformable to fact, and render 
the details of the phenomena more intelligible, to denominate the former, 
what it really is, the external body of the ovule, and not a “ nucleus.” 
t Linn. Trans, vol. xx. p. 2. 
J Ibid, p. 3. 
§ Memoire sur les developpemens et les caracteres des vrais et faux arilles. 
Montpelier, 1844. 
VOL. I. G 
