ORIGIN OF ORGANIC FORMS 



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begun to be differentiated, although not so strongly as 

 to form two distinct lips (fig. 80, 2) : at the same time 

 the five stamens are differentiated in size ; the upper 

 one especially (fig. 80, 2 m) is considerably smaller 

 than the others. On the other hand not all Labiate 

 flowers have a distinctly two-lipped corolla ; e.g. mint, 

 where the flowers are almost regular. Consequently, 



the transition from a regular to a two-lipped corolla 

 might have occurred gradually. Let us pass to the 

 stamens. The Boragineae have five, the Labiatae 

 four, stamens, of which the two lower are larger and 

 the two upper are smaller (fig. 80, 4, n, n). What has 

 become of the fifth ? Whenever an organism lacks 

 an organ, the existence of which can be deduced by 

 analogy with other organisms, we generally find that one 

 of two changes has taken place : the organ has either 

 transformed itself into another organ, undergone a 



