METAMORPHOSIS. 



METAMORPHOSIS. 



804 



1768 would undoubtedly have de*erved to be considered the beginning 

 of a new en in botanical philosophy if it had been known to 

 botanist*. But u it wai introduced into a paper upon the formation 

 of the inUwtinea of animals, it doe* not appear erer to have attracted 

 attention until it was discovered by Miquel a few yean ago. 



It U in reality to the celebrated poet Gothe that the honour justly 

 belong* of baring brought before the world in a clear and philoso- 

 phical manner the doctrine of all the part* of a plant being reducible 

 to the axis and iU appendage*, and consequently of having proved, to 

 u*e his own word*, that vegetable* " develop themselves out of them- 

 selves progressively." By this means he led to the discovery of the 

 real laws of structure, and of the analogies which exist between one 

 thing and another in different tribes of plants; thus laying the 

 foundation of vegetable comparative anatomy by "establishing a 

 principle in harmony with all the laws obeyed by millions of isolated 



A perfect plant consists of branches successively produced out of 

 each other from one common stock, and each furnished with exactly 

 the same organs or appendages as its predecessor. When the fructi- 

 fication is produced, an alteration takes place in the extremity of the 

 fructifying branch, which is incapable, generally speaking, of further 

 prolongation ; but as the branches, before they bore fruit, were repeti- 

 tions the one of the other, so are the branches bearing fruit also 

 repetitions of each other. If a thousand sterile or a thousand fertile 

 branches from the same tree are compared together, they will be 

 found to be formed upon the same uniform plan, and to accord in 

 every essential particular. Each branch is also, under favourable cir- 

 cumstances, capable of itself becoming a separate individual, as is 

 found by cuttings, budding, grafting, and other horticultural processes. 

 This being the case, it follows that what is proved of one branch is 

 true of all other branches. 



It is also known that the elementary organs used by nature in the 

 construction of vegetables are essentially the'same ; that the plan upon 

 which these organs are combined, however various their modifications, 

 is also uniform ; that the fluids all move, the secretions all take place, 

 the functions are all regulated, upon one simple plain ; in short, that 

 all the variations we see in the vegetable world are governed by a few 

 simple laws, which, however obscurely they may be understood by us, 

 evidently take effect with the most perfect uniformity. 



Hence it is not only true that what can be demonstrated of one 

 branch is true of all other branches of a particular individual, but also 

 that whatever can be shown to be the principles that govern the 

 structure of one individual, will also be true of all other individuals. 

 Whatever can be demonstrated to be true with regard to one single 

 individual is true of all other individuals : whatever is proved with 

 reference to one organ is proved by implication as to the same organ 

 in all other individuals whatsoever. 



Moreover, the fact of one organ being readily transformed into 

 another organ is in itself a strong presumption of the identity of their 

 origin and nature ; for it does not happen that one part assumes the 

 appearance and functions of another if they are originally different. 

 Thus, while the functions of the hand may be performed by the feet, 

 as we know they occasionally are in animals, nothing leads the heart 

 to perform the function or assume the appearance of the liver, or the 

 liver of any other organ. This is one of the arguments of Linnaeus. 



The first of the organs which are formed by a modification of leaves 

 are the Bracts ; these bodies are intermediate between the leaves and 

 the calyx. Their nature is extremely various ; sometimes they have a 

 greater resemblance to the leaves, and sometimes to the calyx. In 

 some roses, as Rota canina, they are obviously dilated petioles, to 

 which a leaflet now and then is attached ; in other species, as R. 

 tpinonuima, they differ in no respect from the other leaves. In the 

 tulip a bract is occasionally present upon the scape, a little below the 

 flower ; this U always of a nature partaking both of the leaf and the 

 flower. In Abu* e-ccdta the purple scale-like bracts often become 

 gradually narrower, and acquire a green colour like leaves. It has 

 been stated by some botanists, that bracts are distinguishable from 

 leaves by not producing buds in their axils ; but the inaccuracy of 

 such a distinction U apparent from a variety of cases. In Polygonu.ni 

 rinpartan, and all viviparous plants, the flowers themselves are con- 

 verted into buds within the bracts. There is a bud in the axil of every 

 bract of the rose. The common daisy often bears buds in the axils of 

 the bracts of its involucre ; in which state it is commonly known in 

 gardens by the name of 'hen and chickens.' In the permanent 

 monster called Afutcari monttmum a small cluster of branches covered 

 with minute imbricated coloured leaves resembling bracts is produced 

 in lieu of each flower. Here all the parts of the fructification, instead 

 of remaining at rest to perform their functions, are attempting, but in 

 vain, to become organs of vegetation ; or, in other words, to assume 

 that state from which, for the purpose of perpetuating the species, 

 they had been metamorphosed by nature. Hence it is clear that bracts 

 cannot be essentially distinguished from leaves. [IxvoLUCRUM.] 



With the Calyx begins the flower properly so named ; it forms what 

 some morphologists call the outer whorl of the fructification, and with 

 it commences a new order of leaves, namely those of the fructifica- 

 tion, said to be distinguished from the leaves of vegetation by their 

 constantly verticilUte arrangement, and by the want of buds in their 

 axils. With the leave* of the fructification all power of further 



increase ceases : the energies of the plant being diverted from increas- 

 ing the individual to multiplying the species. The general resemblance 

 of the calyx to the ordinary leaves of vegetation U well known : its 

 green colour, and tendency to develop itself into as many leaves as it 

 consist* of divisions, especially in double roses, is so notorious that it 

 need not be insisted on. In the case of Mettmbryanthc*i barbatum, 

 noticed by Linnams, there is no difference whatsoever between the 

 leaves of the calyx and those of the stem. The resemblance however 

 between the calyx and the stem-leaves is often not apparent ; but the 

 identity of the calyx and bracts is usually more obvious. In Crrtui 

 the transition from the one to the other is so gradual that no one can 

 say where the distinction lies ; and in numberless Ericas the resem- 

 blance of the bracts and calyx is perfect The divisions of the calyx 

 are also occasionally gemmiferous. A case is mentioned by Roper, in 

 which one of the sepals of Caltha paltutrii was separated from the 

 rest, and furnished with a bud. And Du Petit Thouars speaks of a 

 specimen of Brattica naput on which branches were produced within 

 the calyx. A monster of J/errcria jxxrti.Hora ha* been seen of the same 

 nature. (Lindley, ' Introduction to Botany,' ed. 2, p. 533.) From 

 this it is apparent that the divisions of the calyx are not only not 

 distinguishable from bracts, but that there is often a strong tendency 

 in the former to assume the ordinary appearance of leaves. There 

 is however another point to which it is necessary to advert, in order 

 to complete the proof of the identity of calyx and leaves ; this is, 

 the verticillate arrangement of the former. Leaves are either opposite, 

 alternate, or whorled ; and these differences depend wholly upon their 

 greater or less degree of approximation. If the leaves of a plant are 

 rightly considered, they will be found to' be inserted spirally round a 

 common axis ; that is to say, a line drawn from the base of the lower 

 leaf to that of the one above it, thence continued to the next, and so 

 on, would have a spiral direction. When leaves become approximated 

 by pairs, the spire is interrupted, and the leaves are opposite ; let the 

 interruption be a little greater, and the leaves become ternate ; and 

 if the interruption be very considerable, what is called a whorl is pro- 

 duced, in which several leaves are placed opposite to each other round 

 a common axis, as in Qalium. Now a whorl of this nature is exactly 

 of the nature of a calyx, only it surrounds the axis of the plant 

 instead of terminating it As we know that such approximations 

 often take place in the stem in the direct line of growth, where the 

 propulsion of the matter of vegetation exists in its greatest activity, 

 there is no difficulty in comprehending the possibility of such an 

 approximation constantly existing at the end of the system of growth, 

 where the propulsion of the matter of vegetation ceases. But the 

 calyx and more inner whorls of the fructification do not always retain 

 their verticillate position ; on the contrary, they occasionally separate 

 from each other, and assume the same position with regard to the axis 

 of vegetation as is naturally proper to the leaves. This is particularly 

 striking in a very common permanent monster of Liliuni album, known 

 in the gardens by the name of the Double White Lily. In this plant 

 the whole verticillation of the parts of fructification is destroyed ; tho 

 axis is not stopped by a pistil, but is elongated into a stem, around 

 which the white leaves of the calyx are alternately imbricated ; and 

 in double tulips, the outer whorl, representing the calyx, frequently 

 loses its verticillate arrangement, and becomes imbricated like the 

 leaves of a stem. The same structure also occurs in the double white 

 Fritillaria mdeagrU. Hence it cannot be doubted that the calyx 

 consists of leaves in a particular state. 



Tho Corolla forms the second line or whorl of the fructification. 

 It consists of several divisions, usually not green, and always alternate 

 with those of the calyx. It is a series of leaves arising within those 

 of the calyx, from which it is sometimes indeed very easy to distinguish 

 it ; but from which it is so often impossible to discriminate it, that 

 the difference between the calyx and corolla has been one of the most 

 debateable subjects in botany. No limits can be found in Cerent; the 

 same is true of Illicium, and several similar plants. In all Liliacea, 

 Orckidacea, and Zingibcracece, the only distinction that can be drawn 

 between the calyx and corolla is, that the one originates within the other ; 

 they are alike in figure, colour, texture, odour, and function. What- 

 ever therefore has been proved to be true of the calyx is also true of 

 the corolla. There are also cases in which the petals have actually 

 reverted to the state of leaves. In a Campanula Rapunculut, seen by 

 Roper, the corolla had become five green leaves like those of the calyx ; 

 the same was found in a Ytrbatcum pyramidal urn, described by 1 >u 

 Petit Thouars ; proliferous flowers of Geum and Rota, in which tho 

 petals were converted into leaves, are adduced by Linnams. [FLOWER.] 



The third whorl or series of fructification is occupied by the 

 Stamens. These often consist of a single row, equal in number to the 

 divisions of the corolla, with which they are iu that case alternate. 

 The exceptions to this in flowers with a definite number of stamens 

 are not numerous ; and such as do occur are to be considered as 

 wanting the outer row of stamens, and developing the second row 

 instead. Thus in Primvlacca, in which the stamens are opposite to 

 the petals, and therefore belonging to a second whorl, the first makes 

 its appearance in Sdanenckia in the form of clavate or subulate pro- 

 cesses arising from the sinuses of the limb. These, and similar 

 processes, which are far from uncommon in plants, and which are 

 known by various names, such as scales of the orifice of the corolla, 

 glands, nectary, cup, &c., are in most cases metamorphosed stamens. 



