52 Cincinnati Society of Natural History. 



through them, and the sun light is partially excluded. This 

 state of affairs means starvation to the new leaves, which con- 

 tinue to spring from the crowded interior, unless they are able 

 to adapt themselves to the changed conditions resulting from this 

 over-population. Therefore, as the over-crowding continues 

 to increase, the new leaves become "cut pinnatifid." The 

 transition from the large crenate leaves, to the cut-pinnatifid 

 forms, may be observed by any one. The apex of the leaf 

 first becomes cut, the lower portion of the leaf remaining 

 normal. (?) Perhaps two months after the first appearance of 

 these transition forms, the entire leaf has become transformed 

 into a curiously cut-pinnatifid leaf. The large leaves are 

 killed by the early frosts, while the cut leaves, which fill the 

 crown, live through the Winter, and are apparently the 

 growth of early Spring. They are, however, the late Fall 

 growth instead, and are verj- soon superseded by the common 

 large leaves when the real Spring growth begins, passing back 

 through transition forms. 



The variation in the leaves of the common blackberry, 

 Rubus villosus, furnishes another example in which the 

 Spring growth varies from that of the I'all. The leaves are 

 indiscriminately described as having from three to five leaflets. 

 The fruiting cane, however, never produces the quinque- 

 foliate leaf; the tri-foliate form (Fig. i6) is the prevailing leaf 

 on the lower portion of fruiting canes, while toward the 

 extremity but a single leaf is found at the base of the fruit 

 cluster (Fig. i6). The new canes produced during the Sum- 

 mer and Fall, for the next year's fruiting, bear leaves of from 

 three to five leaflets. Various transition gradations occur so 

 commonly (Figs. 14, 15,) on the latter as to be con.spicuous to 

 any one whose attention has been called to the subject. It is 

 interesting to note that the veins become obliterated between 

 these gradation forms, even when the division of the leaves is 

 but begun, as indicated b}- the Figs. 14 and 15, also in 2 of the 

 seedling. (Fig. 13.) But why should not the fruiting canes of 

 the past year's vigorous growth also bear the quinquefoliate 

 leaves and transition forms? Is it not ])ecause the force, 

 which was expended in the prexious h'all in the elaboration 

 of the fruit buds, is now consumed in the production of fruit? 

 Is not this a sort of natural method of pruning? Of hus- 



