542 
MORPHOLOGY. 
BOOK VI. 
CHAPTER II. 
IRREGULAR METAMORPHOSIS. 
It is probable, that all plants have a particular range, in some 
cases more extended than in others, to which they are best 
suited on account of their constitutional peculiarities, which 
become visible in consequence of the effect produced by a 
change of situation, although not appreciable otherwise. The 
two great agents by which they are affected, that is to say, 
soil and atmosphere, will, in their natural situations, be nearly 
uniform. And so long as this uniformity of the conditions 
under which they exist continues, their structure will remain 
unchanged; but let an alteration take place, their atmosphere, 
for instance, change from'; that of the valley to that of the 
mountain, the soil from alluvial deposit to chalk or slate, and 
the mean temperature under which they are formed fall 
several degrees : or remove a plant from its native spot, and 
cultivate it in the rich soil of a garden for several generations; 
thus submitting it to what may be called the effect of domes- 
tication. Under such circumstances, an alteration will be 
produced in the structure of the plant, which will become 
manifest by external characters. This is what is called ir- 
regular metamorphosis ; and may be considered the cause of 
the endless varieties of form into which garden plants are 
continually sporting. In a wild state these varieties are com- 
paratively rare ; while, on the contrary, new forms, miscalled 
species, are always starting up in every botanic garden. In 
the garden of Berlin, Link states that Ziziphora dasyantha, 
after many years, changed to another form, which might be 
called Z. intermedia. 
But although there is no reasonable doubt that irregular 
metamorphosis does take place in consequence of some change 
in the conditions under which plants are formed, the cosmica 
momenta of some writers, yet it is certain that we are entirely 
