162 DI-TRIMEROUS WHORLS AMONG THE FLOWERS OF DICOTYLEDONS. 
* The Ox-eye Daisy,” he writes, “has generally 21 ray-florets at the level of Lake 
Como; but at a height of 400-500 feet a form is developed during the height of the 
flowering season with 34 ray-florets, but it reverts to 21 later on.” 
A remarkable instance of the effect of habitat is seen in Ranunculus Ficaria. In 
Surrey and Guernsey the prevailing number of sepals was 3, or 99 p. c.; that of the 
petals being 8, or 86 p. c. Whereas at Gais the prevailing number of sepals was 5, or 
61 p. c.; while that of the petals was 10, or 29 p. c. The inference I would draw from 
this is that the latter represents the ancestral oer gr aan characteristic of 
the genus (or 2), This has been surrendered to 3 and. ~ in the prevailing 3 sepals 
and 8 petals, in consequence of one cotyledon bun arrested and the foliage 
following suit by being }—just as it is in Monocotyledons generally. This result is 
presumably referable to an ancestral aquatic habit. 
