486 BOTANICAL GAZETTE [MAY 
Proper concentration of hydrogen peroxide proved to be a good forcing 
agent for such of these seeds as would not germinate readily, due to age or other 
causes. A 50 per cent aqueous solution of 8 vol. H.0. completely inhibited 
germination, but 25 per cent and weaker solutions did not, but acted as forcing 
agents. While hydrogen peroxide hastened germination, it retarded the 
growth of the seedling —Wma. CROCKER. 
Age and area ee —WILLIs* has_ recently nibh additional 
evidence to support his “age and area” hypothesis. Following his usual 
statistical method, he shows that the most widespread plants in eles Zealand 
are those which reach outlying islands of the archipelago also. “There is no 
conceivable reason why ranging also to a few little islands should make a 
species more widespread in New Zealand, unless it be age, which has given them 
time to spread in New Zealand to the maximum degree. 
In an accompanying paper the same author* strengthens his hypothesis 
by four additional pieces of evidence, arising from statistics on the following 
situations: the range of the orchids of Jamaica; the flora of Hawaii; the 
my hypothesis, but contrary to what one would expect if endemics are dying 
out.” In conclusion, the author points out that more care must be taken 
to consider geographical as well as structural relationship in forming genera 
and families. 
It occurs to the reviewer to suggest that, in collecting data to support or 
discredit the age and area hypothesis, care should be taken that the plants 
considered are ecologically equivalent. The age and area hypothesis is founded 
on rate of distribution, and the latter certainly must vary as plants vary in their 
ecological status. In some of his more recent researches WILLIS has limited 
his consideration to plants of a given family. This should be more accurate 
than to consider any flora as a whole, for the plants within a given family are 
usually equivalent in their ecological status. This last, however, is not always 
true, so that the significance of some of the data given by WILLIs on distribu- 
tion might sometimes be questioned. For example, it may be quite proper 
to say that widespread fern species are older than fern species of narrower 
distribution, but to state that because ferns are more widespread than angio- 
sperms, the former are therefore older, is very questionable. Even if ferns 
were younger than angiosperms, the ease of spore dispersal si well render 
them more widespread than the latter—MERLE C. CoULTE 
*s WiLLIs, J. C., The distribution of the plants of the outlying islands of New 
Zealand. Ann. Botany 31:327-333. fig. I. 1917 
- rther evidence for age and area; its applicability to the ferns, etc. 
Ann. Botany 31:335-349. I917. 
