1892]. Relation of Fall to Spring Blossoming Piants. 245 
3. Ifthe two facts just noted are more favorable to the de- 
velopment of fall flowering species from spring species by 
direction. The spring flowers which accidentally blossom a 
second time in the fall commonly do not ripen their seeds. 
ow by what kind of selection are these plants ever going to 
acquire gradually the habit of resisting the cold, and ma- 
turing their seeds even after a quite severe winter? If on the 
other hand, the ancestors of fall flowering species began as 
ordinary spring flowers, and then gradually flowered earlier 
and earlier, it may be understood how all these species found 
Some means of resisting the winter cold, and all of them 
gradually acquired the habit of ripening their seeds in spite 
of the cold, either in the spring as usual, or in the fall. It is 
because the habit of flowering in the fall is viewed as the re- 
sult of a gradual development with these species, that a simul- 
taneous development of the power of the fruit to resist cold is 
also readily understood. 
Moreover, the development of the habit of fall flowering in 
the manner just cited requires that the habit of flowering in 
the fall should be formed in the warmer, more southern 
considered, and included in the list III, which does not have its 
Scographical range extending into the districts of southern 
Sardinia, and also why the centre of the area of geographical 
distribution for these species lies usually in the more southern 
ve above investigated derived their habit of flowering in the 
fall in Spai 
be also val 
under simi 
