78 PHILOSOPHICAL NOTES ON 



that is, the inner becomes the outer whorl. I shall proceed to 

 develop this idea further, with the hope of proving that this 

 transposition must have been one of the factors in modifying the 

 forms of flowers, independent of any other factors. 



Some of these endogens have three of their segments with 

 distinctive marks, and in the Iris, it is the three segments of the 

 outer whorl (falls) which are marked. Of course the Iris flower 

 has become so modified, both in its outer and inner whorls, and 

 also in its styles, that it posesses a distinct and characteristic 

 feature. But in Iris Robinsoniana we have all the six segments 

 lying on one level, the three outer, ones or sepals, being marked 

 with a yellow crescent. 



Now in Calochortus, it is the inner segments (what might 

 correspond to the standards in the Iris), which are the marked 

 ones. By what magic has this shifting been brought about ? My 

 reply is that at a certain stage in the evolution of these plants, the 

 inner whorl of the ancestor of Calochortus, became the outer 

 whorl of the ancestor of Iris. 



The reader may say that these two plants are so totally 

 distinct,* that he cannot believe that the petals of Calochortus are 

 homologues of the sepals of Iris. 



Well then I shall take two other flowers, belonging to the 

 same order, the Orchidaceae,! and see if any transposition of 

 whorls can be traced. 



Disa grandiflora has a large upper sepal shaped like a 

 pointed coal-scoop, with a short spur, and beautifully veined ; the 

 lower sepals are two large brilliantly coloured wings. These are 

 the three sepals. Then of the three petals, the upper two are 

 small, spotted, and embrace the column, which, with the two 

 petals, is ensconced in the large spurred sepal, while the lower 

 petal is a dwarfed and insignificant strip. 



Now Angr cecum leonis has its modified segment uppermost,! 

 as in Disa grandiflora, but it is one of the petals that is spurred, 



* Calochortus is classed among Liliacea, and Iris among Iridacea. 



f It should be noted that Lindley's view was that Lilyworts approach so 

 closely to Amaryllids that " there is perhaps nothing to separate them 

 except the free ovary of the one, and the inferior ovary of the other ! " — 

 " Veg. Kingd.," p. 202. 



% It matters little how the modified segment became uppermost or 

 lowermost. 



