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reports on the summer's work and observations. Several from 

 whom reports were expected were unable to be present. 



Professor Francis K. Lloyd gave an account of his summer's 

 experiences at the Desert Botanical Laboratory of the Carnegie 

 Institution at Tucson, Arizona. On the way thither a visit was 

 made to the Tularosa Desert in southern New Mexico. This 

 desert is largely an old lake-bed of a comparatively recent geolog- 

 ical period. The moving white sands which compose the desert 

 overlie the ;//isa and consist chiefly of gypsum, and a little below 

 the surface there is a considerable amount of available water, 

 which, however, is saline. The vegetation of the region is pecu- 

 liar, showing various adaptations to the intense light. Several 

 interesting cases were observed showing how Yuccas and other 

 plants are able by continued vertical growth to keep their tops 

 above the drifts of sand and how in the process they help to build 

 up and hold the dunes. R/i?is trilobata and also a shrubby labi- 

 ate form very marked pillar dunes. The gypsum sand is partly 

 soluble and it solidifies about the vertically elongating roots and 

 stems ; the outer parts of the dune may then erode and be re- 

 moved by the wind, leaving an isolated pillar-like mass sur- 

 mounted by the tops of the living shrubs. An interesting and not 

 especially common plant of the region of Tucson is Cercus Grcggii, 

 of a habit so peculiar and aberrant that it does not seem to be a 

 Ccrciis at all. Like certain other desert plants it has an under- 

 ground storage system which is very large in comparison with the 

 above-ground parts. The rapidity with which foliage appears 

 on desert plants after rains has been often noted and it has been 

 a question in how far growth of leaves may be stimulated by the 

 direct access of water to the above-ground parts without the in- 

 tervention of the root-system. This point was tested during the 

 past summer by experiments at the Desert Botanical Laboratoiy. 

 By means of a siphon, water was supplied directly to the leaf- 

 buds and stems, in such a way as to prevent the water from 

 reaching the ground. It was found that the desert plants thus 

 stimulated produce leaves in the cour.se of a few days. \'ery 

 noticeable changes occur within twent\--four hours, both when 

 plants are stimulated as described and after natural irrigation b}- 



