(33) 
now in preparation. A detailed study of some hybrids of the 
evening-primroses has also been made with a view to a 
comparative study of the hybrid progeny with the parents, 
and with mutants from the same parent. Miss A. M. Vail, 
Dr. G. H. Shull of the Station for Experimental Evolu- 
tion of the Carnegie Institution, and Dr. J. K. Small have 
coéperated with me in this work, the principal results of 
which are to be published by the Carnegie Institution under 
the title ** Mutants and Hybrids of the Oenotheras.” This 
paper is now in press and will be issued in March, 1905. 
A separate series of experiments upon the acquisition of 
new characters and the inheritance of the same has been in 
progress since 1902, but no definite results have been obtained. 
The investigations of the relations of plants to carbon 
monoxide, with Professor H. M. Richards, have been con- 
tinued, and the results are embodied in a lengthy paper 
which will be offered for publication shortly. 
The investigations upon the relations of soil-temperatures 
to vegetation, begun in 1900, have been continued and I now 
have two soil thermographs installed at the Desert Botanical 
Laboratory of the Carnegie Institution at Tucson, Arizona, 
for the purpose of comparison with the results obtained from 
the two instruments installed in the Garden. A new form 
of the Hallock thermograph has been devised in which the 
temperature of the air and of the soil ata single point are 
registered on one recording cylinder simultaneously. 
I have had occasion to visit the Station for Experimental 
Evolution at Cold Spring Harbor, as an associate of that 
institution, for the purpose of consultation with Dr. C. B. 
Davenport and Dr. G. H. Shull upon the work on descent 
and heredity being carried on at that place. 
At the request of Professor de Vries, I have edited and 
revised his lectures upon ‘‘ Species and Varieties: Their Ori- 
gin by Mutation,” delivered at the University of California 
during the summer of 1904. The lectures will appear as a 
single volume of xvili+ 847 pages, published by the Open 
Court Company of Chicago. 
