360 ON SOME REMARKABLE DEVIATIONS

Baked seed not only this kind of fruit, but every monosper- mous pericarpinm bearing a general resemblance to a seed, and ^yllose outer covering, though distinct from the nu- cleus, is only ruptured after germination commences.

Tor the purposes of an artificial arrangement this lan- guage may perhaps be sufficiently accurate ; but in deter- mining the affinities of plants, it is necessary to express by appropriate terms those differences which are no less impor- tant than real.

Of the fruits improperly called naked seeds, there are two principal kinds : the first, in which the pericarpiurn is distinct from the seed, is termed Akena by Richard in his excellent Analyse du Fruit ; the second, in which the pericar- pium coheres Avith the seed, is \}L\^CarijopsisQ>i\kiQ same author.

An Akena (or Achenium), even in a separate state, may in general be readily determined. But it is not always equally easy to distinguish a Cari/opsis from a seed. It may indeed be done in certain cases, as in Grasses, by attending to its surface, in which two distinct and distant cicatrices are observable ; the one indicating the point of attachment to the parent plant, the other that by which it w^as fecundated. In certain other tribes, however, this criterion cannot be had recourse to, the surface of the Cari/- ojjsis exhibiting but one areola or cicatrix, Avhich includes the closely approximated points of attachment and impreg- nation : in such cases, the true nature of the fruit can only be determined by its examination in an earlier stage.

But although it must be admitted that an ovulum is never produced without a covering, through some part of 145] which it is impregnated ; it is still possible to conceive a case in which a ripe seed may be considered as truly naked while retaiiiing its attachment to the parent plant ; and this not subsequent to germination, but even preced- ing the formation of the embryo. For if Ave suppose, as the immediate effect of impregnation, a sw^elling of the ovulum wdthout a corresponding enlargement of the ovarium, the consequence will obviously be a premature rupture of the ovarinm, and the production of a seed provided with its proper integuments only.

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