360 ON SOME UEMARKABLE DEVIATIONS 



naked seed not only this kind of fruit, but every monosper- 

 raous pericarpium bearing a general resemblance to a seed, 

 and whose outer covering, though distinct from the nu- 

 cleus, is only ruptured after germination commences. 



For 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 pericarpium is 

 distinct from the seed, is termed Akena by Richard in his 

 excellent Analyse du Fruit ; the second, in which the pericar- 

 pium coheres with tlie seed , is the Caryopsisoi the 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 Caryopsis from a seed. It 

 may indeed be done in certain cases, as in Grasses, by 

 attending to its surface, in Avhich two distinct and distant 

 cicatrices are observable ; the one indicating the point of 

 attachment to the parent plant, the other that by which it 

 was fecundated. In certain other tribes, however, this 

 criterion cannot be had recourse to, the surface of the Cary- 

 opsis exhibiting but one areola or cicatrix, which includes 

 the closely approximated points of attachment and impreg- 

 nation : in such cases, the true nature of tlie fruit can only 

 be determined by its examination in an earlier stage. 



Birt although it must be admitted that an ovulum is 

 never produced without a covering, through some part of 

 146] which it is impregnated ; it is still possible to conceive 

 a case in which a ripe seed may be considered as truly 

 naked while retaining its attachment to the parent plant ; 

 and this not subsequent to germination, but even preced- 

 ing the formation of the embryo. For if we suppose, as the 

 immediate effect of impregnation, a swelling of the ovuluin 

 without a corresponding enlargement of the ovarium, the 

 consequence will obviously be a prematm-e rupture of the 

 ovarium, and the production of a seed provided with its 

 proper integuments only. 



