INDEX TO AMERICAN BOTANICAL LITERATURE 155 
Osterhout, W. J. V. A comparative study of permeability in plants. 
Jour. Gen. Physiol. 1: 299-304. f. 1, 2. 20 Ja 1919. 
Osterhout, W. J. V. Endurance of extreme conditions and its relation 
to the theory of adaptation. Am. Jour. Bot. 5: 507-510. f. zr. D 
1918. 
Osterhout, W. J. V. A simple method of demonstrating the production 
of aldehyde by chlorophyll and by aniline dyes in the presence of 
sunlight. Am. Jour. Bot. 5: 511-513. D 1918. 
Osterhout, W. J. V., & Haas, A.R.C. The temperature coefficient of 
photosynthesis. Jour. Gen. Physiol. 1: 295-298. 20 Ja 1919. 
Oswald, W. L., & Boss, A. Minnesota weeds—III. Minnesota Agr. 
4: Exp: Stay Ball. 176: 6-42. f.1-25. JV 1018, 
Pennell, F. W. Symphoricarpos Symphoricarpos. Addisonia 3: 
61, 62. pl. I1z. 30 Di1918 
Petrak, F. Die nordamerikanischen Arten der Gattung Cirsium 
Bei. Bot. Centralb. 32: 223-567. f. 7. 1917. 
Includes many new combinations. ~ 
Piper, C. V. Some western species of Lathyrus. Proc. Biol. Soc. 
Washington 31: 189-196. 30 D 1918. 
Pulling, H. E. Root habit and plant distribution in the far north. 
Plant World 21: 223-233. f. 7. S 1918. 
Ramaley, F. Notes on dune vegetation at San Francisco, California. 
Plant World 21: 191-201. f. 1-4. Au 1918. 
Ridgway, C.S. <A promising chemical photometer for plant physiolog- — 
ical research. Plant World 21: 234-240. S 1918. 
Published also in the Monthly Weather Rev. Mr 1918. 
Robbins, W. W., & Egginton, G. E. Alfalfa dodder in Colorado. 
Colorado Agr. Exp. Sta. Bull. 248: 1-15. f. 1-8. N 1918. 
Rolf, R. A. Odontoglossum praevisum. Curt. Bot. Mag. IV. 14: 
pl. 8780. 1918. 
A plant from Colombia. 
Rolfe, R. = Cereus Tunilla. Curt. Bot. Mag. IV.14: pl. 8779. 1918. 
A plant from Costa Rica. : 
Rolfe, R. A. Phaius grandifolius in Panama. Orchid Rev. 26: 119, 
120. O1918 
Shamel, A. D. Lemon orchard from buds of single selected tree. 
Jour. Heredity 9: 319, 320. f. 10. 12 D 1918. 
Shamel, A. D., & Pomeroy, C. S. A fruiting orange thorn. Jour. 
Heredity 9: 315-318. f. 8,9. 12 D 1918. 
