220 
classes which are wont to occur in the second hybrid generation. 
Space for such experiments is scarcely available, as planes do 
not assume for several years their adult foliage, and do not pro- 
duce fruit till they are twenty or thirty years old. 
“The artificial production of a cross between P. orientalis and 
P. occidentalis has not been possible in this country, where there 
exists no adult living tree of the latter species from which pollen 
could be obtained. An attempt to reproduce P. acerifolia by 
cross-pollination of the Occidental and Oriental Planes might 
be made in the United States, using the native tree as the female 
parent.” 
THE SCIENTIFIC SURVEY OF PORTO RICO AND THE 
VIRGIN ISLANDS 
In 1913, the New York Academy of Sciences in codperation 
with the insular government of Porto Rico, The American Mu- 
seum of Natural History, The New York Botanical Garden, and 
with scientific departments of Columbia University and other 
institutions, commenced an investigation of the geology and 
natural history of Porto Rico, which was subsequently extended 
to include the Virgin Islands. Field, museum and laboratory 
work have since been prosecuted by a large number of investi- 
gators and students of the several institutions, and although 
much interrupted and retarded by war conditions, the study is 
well advanced, and some 36 preliminary papers have been pub- 
lished in various journals and bulletins of institutions and in the 
proceedings of learned societies. The collections of the institu- 
tions have been entiched by many thousand specimens obtained 
during the field operations. 
The first part of the first volume of the final reports of this 
Survey was published on September 26th, 1919, and may be 
purchased from the Secretary of the Academy. It is an octavo 
book of 110 pages, with 26 text-figures, 4 plates and 3 maps, and 
contains (1) A History of the Survey, with references to the 
already published preliminary papers, by Dr. N. L. Britton; 
(2) Geological Introduction, including a discussion of the major 
