6o re;ports on investigations and projects. 



of evolution, especially in the formation of specific types through the syn- 

 thetic recombination of existing attributes. The behavior of these stable 

 races, produced through these experiments, is precisely that of many species 

 in nature, and some of them (in their permanent dimorphism or polymorph- 

 ism) are in all respects similar to dimorphic and polymorphic species in 

 nature; and their activities (especially in analytical experiments) leads me 

 to believe that the numerous instances of dimorphism and polymorphism 

 probably have a similar origin in nature. The present cultures of this type 

 will be continued and an increased array of investigations of this sort will be 

 initiated in the future. During the years 1910 and 1911 there have been 

 introduced into the cultures at the laboratory a considerable number of stable 

 hybrid combinations which were produced in the laboratories at Chicago, 

 many F^ hybrids, and a considerable number of new creations from the same 

 source. These are being tested as to their capacity to survive under the 

 desert conditions, the possibility of being further modified by changed en- 

 vironment, and the possible reversion to the original condition. Thus far 

 not the slightest trace of reversion in the Darwinian sense has been dis- 

 covered. The season of 1911 marks the close of four years of operations 

 at this station, and during these years a considerable body of data has been 

 collected, from which some of the broader lines of investigation, with the 

 conclusions thus far derived, are here indicated. These years have been, 

 however, more in the nature of a preparatory period in the perfection of 

 methods and the ability to handle the natural environmental complex for 

 experimental purposes to the best advantage. These methods of work, the 

 results obtained, and the determinations of the physical environment that 

 have been made will be ready for publication in the near future. 



Certain of the experiments now under way at the laboratory will be brought 

 to an end this year and in their place new and more complicated investiga- 

 tions are being organized. For that portion of my work requiring a desert 

 location, none better than that found at the Desert Botanical Laboratory 

 could be desired. The advantageous location, the interest taken by the Di- 

 rector of the Laboratory in facilitating this work, and the liberality of the 

 Carnegie Institution of Washington in providing anything that has been 

 needed in the investigation have contributed much to the rapid progress 

 which it has been possible to make in the four years of operations. 



Botanical Features of Algerian Deserts, by Dr. W. A. Cannon. 



Dr. Cannon started from Algiers in October 1910, and followed a route 

 in the desert which carried him across the Tell, the High Plateau, and the 

 Atlas Mountains nearly directly southward to Laghouat and Ghardaia, then 

 to Touggourt by way of Ouargla. From Touggourt the return was made 

 by the Oued Rirh to Biskra, thence to the starting-point. The entire jour- 

 ney included over 1,000 miles of desert travel by diligence, motor cycle, and 

 camel train. A brief trip was made also up the Nile as far as Assouan to 



