116 BOTANICAL GAZETTE [JANUARY 
Endemism.—RIMLEv™ recently presented a series of criticisms of the 
work of WiLtis on endemism in Ceylon. Wuuis had attempted to demon- 
strate by the statistical method that endemics were the most recent rather than 
the most ancient forms in a given locality. In his criticism RipLEy objected 
that the statistics used were inaccurate, pointing out a number of flaws. In 
addition he presented from his own experience some striking exceptions to the 
general conclusion of Wittis. In conclusion, RmLEy objected to the use 
Wit.is had made of the mutation theory, RmpLey himself evidently being a 
confirmed natural selectionist. 
Wis has now answered these criticisms in a rather satisfactory way. 
As to the flaws in his statistics, he points out how they are quantitatively of 
little significance. As to the applicability of his conclusions, he presents two 
crucial cases: (1) showing that the widely distributed forms of New Zealand 
“take no notice” in their distribution of Cook’s Strait (of relatively recent 
origin), while the endemics do; (2) the “local distribution of the highly modi- 
fied Tristichaceae and Podostemaceae and the cosmopolitan distribution of the 
little modified forms.’”’ As to man’s action, changes of climate, and similar 
disturbing factors which Rm rey had accused him of neglecting, WILLIS 
stated that these, although they may exert a disturbing influence, no more 
affect the validity of his law than does the resistance of air effect the law of 
gravity. Finally, Writuis deals with Riiey’s theoretical objections merely 
by pointing out that natural selection cannot explain the origin of the peculiari- 
ties which distinguish plants, but can only preserve or destroy them when once 
ormed. 
In an accompanying paper SINNOTT” raises additional objections to the 
hypothesis of Wituis. He says that “other factors than age determine the 
area occupied by a species.” He can hardly claim, however, that this affects 
the validity of the law. He also states that the data of W1.ts would seem to 
indicate that woody plants are producing new species faster than are herbs, a 
conclusion against which there is much evidence; and likewise they would 
indicate that herbs are the older since they are the more widely distributed. 
Battery and Sinnott had previously stated and substantiated the contrary 
view. May not the two ideas be reconciled, however, by the fact that it is 
the nature of herbs to spread the more rapidly, due to more meager require- 
ments for germination and to more extensive vegetative multiplication ? 
swamping”’ of isolated members of old species by crossing with newly devel- 
™ Rev. in Bor. Gaz. 64:263. 1917. 
*% Wituis, J. C., The relative 805 of endemic species and other controversial 
points. Ann, Botany 31:189~208. 19 
%6 Sinnott, Epmunp W., The “age and area” hypothesis and the problem of 
endemism. Ann. Botany 31: 2097206, 19 
