Plant Geography. — Phenology. 45 
plant development. In line with these is DARRACH’s Plants appearing in 
Flowers in the Neighborhood of Philadelphia February to November 1883. 
The general works on American phenology are few. Modern Meteor- 
ology by WaLpo, published in 1893, contains an important resume. The 
Advent of Spring an article by MARK W. HARRINGTON, which appeared in 
Harper’s Magazine in May 1894, describes the advance of the southern wave 
of 43.8° F. northward across United States, when Spring may be said to begin. 
CHARLES ROBERTSON contributes to the twenty-ninth volume of the American 
Naturalist, a paper entitled the Philosophy of the Flower Seasons and the 
Phaenological Relations of the Entomophilous Flowers and the Anthophilous 
Insect Fauna, and HENRY CLARKE to the twenty-seventh volume of the same 
journal (1893) the Philosophy of the Flower Seasons, while J. W. HARSHBERGER 
contributed to Science an article on the origin of the vernal flora. Instructions 
for taking Phenological Observations by L. H. BAILEY was abstracted from 
Monthly Weather Review for September 1896, while the same botanist devotes 
two chapters to a phenologic discussion in his book, the Survival of the Unlike. 
These Chapters were the outcome of a paper prepared for the Weather Bureau 
United States Department of Agriculture entitled Some Suggestions for the 
Study of Phenology. He gives speculative note on phenology the interrelations 
of climatology and horticulture while a chapter is devoted to acclimatization. 
The field work of ‚the Division of Biological Survey of the U. S. Department 
of Agriculture is based on the publications of C. HART MERRIAM, who founded 
his system on the laws of temperature control of the geographical distribution 
of terrestrial animals and plants, essentially phenologic data. Finally should 
be mentioned the excellent records kept by members of the Botanical Society 
of Pennsylvania. These incorporated with those kept by RAnD of Radnor, 
Pa. for a long series of years have been correlated and classified for future 
reference use. 
It is clearly evident, therefore, that the American literature on phenology 
’S very meagre and that the so called phenologic observations have been mere 
records of dates of blooming of flowers, leafıng of trees, migration of birds, 
Peeping of frogs and the like, without much correlative data respecting the 
local climate. 
Chapter IL. Bibliography. 
The titles in the following lists are arranged first geographically and then 
we habetically according to the names of the authors as the most convenient 
method .of displaying the names of books and papers upon the North American 
Mora. The titles of a number of works, or monographs, which deal with the 
. Physiography, geology and geography of the several regions are also included, 
°° fhat the following enumeration, very restricted as it is, yet gives the more 
