36 MORPHOLOGICAL DEVELOPMENT. 



flower? are brought into a cluster ; as they are in the cows 

 lip. On contemplating a clover-flower, in which this 

 clustering has been carried so far as to produce a com 

 pact head ; and on considering what must happen if, by a 

 further arrest of axial development, the foot-stalks of the 

 florets disappear ; it will be seen that there must result a 

 crowd of flowers, seated close together on the end of the axis. 

 And if, at the same time, the internodes of the upper stem- 

 leaves also remain undeveloped, these stem-leaves will be 

 grouped into a common calyx or involucre : we shall have a 

 composite flower, such as the thistle. Hence, to modifications 

 in the developments of foliar organs, have to be added modi 

 fications in the developments of axial organs. Comparisons 

 disclose the gradations through which axes, like their append 

 ages, pass into all varieties of size, proportion, and structure. 

 And we learn that the occurrence of these two kinds of 

 metamorphosis, in all conceivable degrees and combinations, 

 furnishes us with a proximate interpretation of morpho 

 logical composition in Phcenogams. 



I say a proximate interpretation, because there remain 

 to be solved certain deeper problems ; one of which at once 

 presents itself to be dealt with under the present head. 

 Leaves, petals, stamens, &c., being shown to be homologous 

 foliar organs ; and the port to which they are attached, 

 proving to be an indefinitely- extended axis of growth, or 

 axial organ ; we are met by the questions, What is a foliar 

 organ ? and What is an axial organ ? The morphological com 

 position of a Phsenogam is undetermined, so long as we can 

 not say to what lower structures leaves and shoots are homo 

 logous ; and how this integration of them originates. To 

 these questions let us now address ourselves. 



190-1. Already, in 78, reference has been made to the 

 Dccasional development of foliar organs into axial organs: 

 che special case there described, being that of a fox- glove, in 

 *rhich some of the sepals were replaced by flower-buda 



