REFERENCES 



ECONOMIC BOTANY.— Publications of the Bureau of Plant Industry, Depart- 

 ment of Agriculture, from January 1 to June 30, 1912, as follows: An improved 

 7iiethod of artificial pollination in corn. G. N. Collins and J. H. Kempton. 

 Circular No. 89. Pp. 7, figs. 2. 



A plant-disease survey in the vicinity of San Antonio, Texas. Frederick 

 D. Heald and Frederick A. Wolf. Bulletin 226. Pp. 129, pis. 19 and 

 figs. 2. 



Absorption and excretion of salts by roots, as influenced by concentration and 

 composition of culture solutions. Rodney H. True and Harley Harris 

 Bartlett. Bulletin 231, Pp. 36, pi. 1, figs. 21. 



Wild volatile-oil plants and their economic importance: I. Black Sage; II. 

 Wild Sage; III. Sivamp Bay. FranK Rabak. BulletiN 235. Pp. 37, figs. 6. 

 The wilting coefficient for different plants and its indirect determination. Lyman 

 J. Briggs and H. L. Shantz. Bulletin 230. Pp. 83, pis. 2, and figs. 9. 

 Agricultural varieties of the cowpea and immediately related species. C. V. 

 Piper. Bulletin 229. Pp. 160, pis. 12. 



Heterozygosis in evolution and in plant breeding. E. M. East, assisted by 

 H. K. Hayes. Bulletin 243. Pp. 58, pis. 8. 



ENGINEERING. — Publications of the Office of Public Roads, Department of Agri- 

 culture, in 1912, as follows: Inorganic road Materials. E. C. E. Lord. To 

 be published in the Year Book, 1912. 



Highway bridges and culverts. Charles H. Hoyt and William H. Burr. 

 Bulletin No. 43. 



The physical testing of rock for road building. Albert T. Goldbeck and 

 Frank H. Jackson, Jr. Bulletin 44. 



The physical testing of broken stone railroad ballast. A. T. Goldbeck and F. 

 H. Jackson Jr. Paper before the International Association for Testing 

 Materials. Vlth Congress. 1912. 



Oil-mixed portland cement concrete. Logan Waller Page. Bulletin 46. 

 Effect of diameter of bitumen holder on the penetration test. C. S. Reeve, Office 

 of Public Roads. Sixth Congress of the International Association for Test- 

 ing Materials. 1912. 



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