90 VEGETABLE ORGANOGRAPHY. 



become double, which is frequently the case, the stamens 

 are transformed into petals so similar to the pieces of the 

 perigone that it is difficult not to believe that they are of 

 a very analogous nature. 



If we add to these reasons, that this envelope is often 

 green on the outside and coloured internally, that it 

 alwavs has stomata on the outer surface and none on 

 the innner, we shall perhaps be inclined to conclude, 

 that this perigone is formed of a calyx lined, thus to 

 speak, with a petaloid expansion of the torus. I have 

 only given this opinion as a simple hypothesis ; but I 

 think that it is more prudent, in the actual state of 

 the science, not to adopt terms which decide the ques- 

 tion too clearly, and that it is well to retain for these 

 doubtful cases of a single envelope a particular name. 

 I have adopted, after Ehrhart, that of Perigone, which 

 signifies, around the sexual organs ; and following the 

 analogy of the terms sepals and petals, I propose to give 

 to the pieces of which it is formed the name of Tepals. 



Some authors, adopting my idea, have given the single 

 envelope the name of Perianth ; but I think it better 

 to retain that of perigone : — 1st, because that of peri- 

 anth was understood by Linnaeus to designate the true 

 calyx ; 2d, because this term, which signifies around 

 the flower, would be more applicable to an involucrum 

 than to an organ which forms part of the flower ; 3d, 

 because the word perigone has been proposed in this 

 sense before that of perianth, and we ought always to 

 avoid useless changes of nomenclature. The term beina: 

 once admitted, we must apply to the perigone all that 

 has been said of calyces and corollas, inasmuch as 

 they are formed of pieces, sometimes free, at other 

 times cohering ; all that has been said of calyces, as 

 regards their adhesion with the ovary ; and all that has 

 been said of petals, inasmuch as they are analogous to 



I 



