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the citizens of Tucson was given under the pene of the Lab- 
oratory, and of the University of Arizona. t the invitation of 
Mr. J. J. Thornber, Botanist of the Agricultural Experiment Sta- 
tion, selections were made from the nursery of young indigenous 
plants on the university grounds and from Mr. Thornber’s private 
collection, for shipment, and these have already been installed in 
the greenhouses increasing materially the already large number 
of accessions due to the kind codperation of Mr. Thornber. 
rrangements were also made to receive a large set of herbarium 
specimens from Arizona in exchange. 
My plans included the descent of the Rio Colorado from 
Yuma, Arizona, to the Gulf of California for the purpose of mak- 
ing an examination of the vegetation of the great delta of the 
river, and of the deserts contiguous in Sonora and Baja Cali- 
fornia. By agreement with Mr. G. Sykes, civil engineer of Flag- 
staff, Arizona, he had proceeded to Yuma early in November 
and begun the construction of a small sloop of a design specially 
suitable for the work to be carried out. This boat was flat bot- 
tomed for floating over the hundred and fifty miles of muddy shal- 
lows that lay between us and the gulf, and was furnished with a 
centerboard to be used in navigating the deeper waters to be en- 
countered there, and -was rigged to receive a mainsail and jib. 
A complete camping equipment, provisions, instruments and 
collecting outfit weighing in all about twelve hundred pounds 
was placed aboard the boat, which thus loaded had a draft of nine 
to twelve inches, about as deep as could be comfortably taken 
down the stream at this low stage of the water. The party also 
included Prof. R. H. Forbes, Director of the Experiment Station 
at Tucson, and an assistant. 
A start was made from Yuma at noon on January 28, and six 
lays were consumed in floating down the river a distance of a 
hundred miles to the last outpost of settlement, Colonia Lerdo, 
on the Sonora shore of the river. This slow rate of progress 
made it possible to go ashore frequently and examine the delta, 
and in three places the stream cuts directly into the gravelly 
deserts of Sonora, bringing the vegetation of the lowland and 
margins immediately in contact with that of the desert, a condi- 
