274 Professor Owen on Metamorphosis and Metagenesis. 



ganism which retains the primitive condition of cells, is the 

 power of producing new individuals without receiving a fresh 

 supply of the pollen-principle. 



Thus in a plant, when the seed has received the matter of 

 the pollen-filament, analogous changes take place to those 

 that have been described in the animal egg, and the embryo 

 plant appears in the form of the cotyledonal leaf with its 

 radicle or rootlet. From this shoots forth another leaf with 

 its stem : and the cellular substance of the pith with its share 

 of the pollen-principle goes on developing fresh leaves and 

 leaf-stalks ; until a provision for developing fresh pollen is 

 made by transforming certain individual leaves into a higher 

 form of the ' phyton' or elemental plant. Thus a generation 

 or ' whorl' of leaves assumes the character of sepals, another 

 that of petals, a third that of stamens, a fourth that of pis- 

 tils : and in the two latter forms we recognise the analogues 

 of the perfect male and female of the animal. 



The development of the compound polype follows very 

 closely the stages of the compound plant, which we call shrub 

 or tree : the ovum, like the seed, having received the pollen- 

 principle, is converted into countless cells and nuclei of cells 

 by the process for diffusing that principle through, or of as- 

 similating it with, the matter of the Q^g. Then certain germ- 

 cells are metamorphosed into a ciliated integument, and the 

 larva starts forth, in a state answering to the cotyledonal leaf 

 of the plant; the ciliated larva settles, subsides, and shoots up 

 a stem from which a digestive polype is developed, answering 

 to the leaf : but the pollen-force not being exhausted, a 

 second branch and polype are developed, and so on until a pre- 

 paration is made for a fresh supply of pollen-force, by meta- 

 morphosing the polype into a higher form of individual ; and 

 this, in many compound polypes, is set free in the shape of a 

 minute medusa. 



The true nature and relation of the individual polype to 

 the compound whole is well illustrated by the propagations 

 of the Aphides. 



By comparing with the diagrams of the metagenesis of the 

 plant and polype, that of the Aphis, in which was represented 

 the corresponding stages intervening between the ovum and 

 the perfect male and female individuals of the Aphis, the 



