1919] Hallr-Goodspcrd: ('hrijsil 187 



invaluable aid in the establishment and operation of our own labora- 

 tory', where the later analyses have been made by the junior author 

 and Miss Mildred Crane. Dr. David Spence, Chairman of the 

 Subcommittee on Rubber and Allied Substances of the National Re- 

 search Council, has superintended the extraction and vulcanization of 

 rubber from sample shrubs sent him and has given opinions from time 

 to time regarding our metliods and the quality of the product. Dr. 

 W. B. McCallum, and Professor Francis E. Lloyd, both recognized ex- 

 perts on Guayule production, have made many valuable suggestions. 

 Mr. E. C. McCarty of the University of California made a field trip of 

 two weeks' duration into central Nevada for the purpose of collecting 

 samples and making estimates as to the occurrence and distribution of 

 certain species and Mr. J. R. Bruff, of the same institution, spent two 

 weeks on such work in northern California and Nevada and southeast- 

 ern Oregon. Professor Marcus E. Jones, of Salt Lake City, has per- 

 formed a similar service in Utah. He spent a total of twenty days in 

 the field and in addition has contributed freely from his very de- 

 tailed knowledge of the botany and distribution of the shrubs through- 

 out the Great Basin Area. Through the courtesy of Dr. Frederic E. 

 Clements, of the Carnegie Institution of AVashington, the senior au- 

 thor, was enabled to spend a month in field studies extending from 

 Oregon to New Mexico. It is a pleasure to acknowledge also the as- 

 sistance of Professor W. A. Setchell, head of the Department of Bot- 

 any of the University of California, who has supported the work 

 throughout both by his sympathy and advice and by making it pos- 

 sible for the authors to give to it a larger portion of their time than 

 is ordinarily available for investigational work. The laboratories and 

 herbarium of the Department of Botany have been freely used and 

 much of the expense has been borne by the University. Grants have 

 also been made, more especially for field expenses, by the Committee 

 on Scientific Research of the State Council of Defense of California. 

 The list of friends who have sent information and samples, often 

 at much trouble, includes the following: Mrs. Sidney Armer, Berke- 

 ley; Mr. W. W. Blakeslee, U. S. Forest Service; Mr. Fred E. Burlew, 

 Los Angeles; Miss Ethel J. Case, Spokane; Mr. John Dondero, Mono 

 Lake; Mrs. Roxana S. Ferris, Stanford University; Mr. M. French 

 Oilman, Banning; Mr. Benj. J. Holfner, U. S. Forest Service; Mr. 

 Edmund C. Jaeger, Palm Springs; Mr. Geo. C. Larsen, U. S. Purest 

 Service; Mr. AV. M. Maule, U. S. Forest Service; Mr. James W. Mc- 

 Gow^an, U. S. Forest Service; Mr. Alexander McQueen, IT. S. Forest 



