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be farther changed towards the true character of petals ; but the first 

 change of the component parts of the pistil into leaves, implies that 

 this organ is constructed of the same elements which, in some other 

 portions of the plant, are devoted to other purposes ; and the fact of 

 their changing first into leaves, leads to the inference that the pistil, 

 in its younger state, is more or less employed in connexion with the 

 purposes of nutrition as well as of reproduction. 



Instances of such kinds of metamorphosis as that just alluded to, 

 are very common in " flowering plants," but such deviations from the 

 normal state are more rarely witnessed among the "flowerless plants." 

 Still, it can be observed, that the beautiful law of causing leaves un- 

 der different states of modification to constitute the organs concerned 

 in the perpetuation of the species, as well as in the assimilation of 

 nourishment, obtains even in some of the higher orders of flowerless 

 plants. 



In certain ferns it may occasionally be seen that a group of minute 

 leaves occupies the position of the part appropriated to the minute 

 organs of reproduction {sorus), clearly demonstrating that the cap- 

 sules which are replaced by leaves, must have a common origin with 

 them : and Professor Lindley, in the 2nd edition of his ' Introduction 

 to the Natural System of Botany,' p. 398, compares the annulus of 

 the capsule of a fern to the midrib of a leaf; the membranous case of 

 the sporules to the blade, and the peduncle to the petiole. 



Since occurrences of this kind have been witnessed in the ferns, 

 which departure from the ordinary character of these organs has 

 enabled us to understand their structure, Professor Lindley has sug- 

 gested the idea that the structure of the fruit of mosses may be con- 

 formable to the same law, after the following manner. "The calyptra 

 may be understood to be a convolute leaf; the operculum another ; 

 the peristomium one or more whorls of minute flat leaves; and the the- 

 ca itself to be the excavated distended apex of the stalk, the cellular 

 substance of which separates in the form of sporules." — Introd. Nat. 

 Syst. 2nd ed. p. 408. 



It does not appear that specimens had been discovered by which 

 the identity of the origin of the several parts of the fructification of 

 a moss with true leaves could be demonstrated, and thus confirm the 

 above supposition : I have however lately examined some specimens, 

 which go far to prove that these minute organs are capable of being 

 converted into leaves, leaving but little doubt that modifications of 

 leaves are here employed, as in ferns and the higher orders of plants, 

 to constitute the parts concerned in the duty of reproduction. 



