438 
aspects of departmental affairs and re- 
searches. 
DEPARTMENT OF BOTANICAL RESEARCH 
The activities of this department now 
necessarily cover a wide range, since any 
successful attempt to solve the problems of 
the origin, development, migration, and 
modification under varying climatic condi- 
tions of plant life must require extensive 
field observations, much laboratory experi- 
mentation, and increasing application of 
the sciences of chemistry and physics. It 
is natural and proper, therefore, that the 
staff and collaborators of the department 
should include many specialists, and that 
they should approach the problems to be 
investigated from many points of view. 
Thus it happens that the investigations of 
the past year have embraced, among others, 
studies of the evaporation, the increasing 
salinity, and the changes in vegetation fol- 
lowing close after the receding shores of 
the Salton Sea; of the influences of tem- 
perature, rainfall, sunlight, soil-moisture, 
ete., on plant organisms; of the effects fol- 
lowing transplantation from low to high 
altitudes and from arid to humid localities; 
of the variations in water and acid content 
of plants; of the chemical effects induced in 
plant tissue by light and heat; and of the 
physiological functions of leaves in plant 
life. 
One of the most interesting investigations 
under way during the year is that of Dr. 
Ellsworth Huntington, research associate 
of the department, on the secular variations 
of climate of the southwest desert area in 
recent geologic time. From this work it is 
believed that some of the salient fluctua- 
tions in climate during the past two or 
three thousand years may be clearly made 
out. Another noteworthy investigation of 
the year is that of the respiration of cacti, 
undertaken by Professor H. M. Richards in 
SCIENCE 
[N.S. Vou. XXXV. No. 899 
collaboration with the department. This 
has developed the remarkable fact of a defi- 
nite diurnal periodicity in the acid content 
of the sap of the cacti under observation. 
The progress and status of many other in- 
structive investigations are set forth at 
length under the twenty subdivisions of the 
director’s report, to be found in full in the 
current year book. From this it appears 
that, in addition to the regular and asso- 
ciate members of the staff of the depart- 
ment, about an equal number of individual 
investigators have collaborated in the re- 
searches under way. Special attention may 
be here invited to the detailed account given 
in one of the subdivisions of this report by 
Professor Tower in reference to his further 
experiments on the evolution of chrysomelid 
beetles, the results of his early work in this 
line under the auspices of the institution 
having been issued as publication No. 48. 
DEPARTMENT OF EXPERIMENTAL EVOLUTION 
It is a well-known fact that important 
generalizations in science usually leave a 
multitude of details to be worked out. In- 
deed, advances often raise more questions 
than they settle. Such has been the won- 
derfully fruitful effect of the doctrine of 
evolution propounded by Darwin, Spencer, 
and Wallace a half century ago. It should 
not be surprising, therefore, that the pro- 
gram of the Department of Experimental 
Evolution presents a considerable variety of 
investigations related to the highly complex 
problem of heredity chosen by the director 
as the principal object of research. Thus 
the work of the year includes investigations 
of heredity in plants, insects, birds, ani- 
mals, and man. 
One of the most promising investigations 
of the year is that of the director in refer- 
ence to the heredity of epileptics. Through 
his connection with the Eugenics Record 
Office, he has collaborated with Dr. David 
