(32) 
The lectures by Professor de Vries upon ‘* Species and 
Varieties: Their Origin by Mutation” delivered at the Uni- 
versity of California during the summer of 1904 were edited, 
and issued as a book of xviii + 847 pages by the Open Court 
Co. of Chicago. The first edition having been exhausted a 
second was prepared with the assistance of Miss A. M. Vail, 
in November and December, which will be issued under date 
of January, 1906. 
The researches upon soil-temperatures have been continued 
at the Garden and at the Desert Botanical Laboratory at Tuc- 
son, Arizona. By the coéperation of Dr. Forrest Shreve, I 
have been able to have a third series of instruments at our 
tropical laboratory, at Cinchona, Jamaica. 
I have continued to coéperate with the Station for Experi- 
mental Evolution at Cold Spring Harbor, L. I., and have 
made several visits to the place during the summer. 
Early in March an expedition was organized which started 
from the Needles, at Mellen, Arizona, and descended the 
Colorado River in two small boats, one of which was fitted 
with a cage for carrying cacti. I was accompanied on the 
part of the trip from the start to Yuma by Mr. G. G. Copp, 
of New York, and Mr. Stanley Sykes, of Rhoades, Arizona. 
A large number of living specimens of cacti were obtained 
from both the Arizona and California shores, and it was defi- 
nitely ascertained that Cereus giganteus is a component of the 
flora of California. At Yuma, Arizona, the expedition was 
joined by Mr. Godfrey Sykes, who had previously accompa- 
nied mein a trip to the lower part of the river, and by Mr. E. 
A. Goldman, of the U.S. Biological Survey. A new boat was 
built and the river was descended to the estuary and then the 
course was laid up the Hardy for the Cucopa mountains 
which had not previously been visited by a botanist. An in- 
teresting collection of living and preserved material from 
here and from the salt and alkaline desert near the mud-vol- 
canoes was secured. In addition to extensive data bearing 
upon the geography of the region, some important facts as to 
desert vegetation were obtained. The principal results are 
