EXTRACT XLIV.A. 



ON METAMORPHISM. 



METAMORPHISM, or the process of metamorphosis of 

 tissue materials, is observed in the evolution and growth 

 of all vital organisms, as well as in the involution and 

 decadence of these organisms as displayed in post-primal 

 age or the " decline of life." 



Metamorphoses of tissue formation and, in many cases, 

 of external form, are so numerous and apparent, and have 

 been so exhaustively treated and elucidated by the botanist 

 and zoologist throughout the two kingdoms of animated 

 nature, that it seems unnecessary to do more than call the 

 attention of those interested in the subject, in so far as it 

 relates to their peculiar departments of science, in order 

 that the evolutionary processes of metamorphism may be 

 utilised to explain and illustrate the converse, or reverse, 

 involutionary processes of metamorphism undergone by 

 vital textures in their period of decline and devitalisation 

 or resolution. 



Evolutionary metamorphosis, as here implied, may be 

 shortly described as a process of change from a lower to a 

 higher form of structural arrangement and functional role, 

 whereby a stage of stable and perfect formative attainment 

 is ultimately reached by the organism in its various parts 

 and textures where, and in which condition, it continues 

 for a variable period according to the nature of the 

 organism, when, or after which, a process of decline or 

 involution sets in, and lasts till the vital cohesion of its 

 component structural parts can no longer be maintained, 

 and death ensues as the inevitable consequence. These 



