INDEX TO AMERICAN BOTANICAL LITERATURE 75 
Greaves, J. E. & Carter, E.G. Influence of moisture on the bacterial 
activities of the soil. Soil Sci. 10: 361-387. f. 1-4. N 1920. 
Hauman, L. Un viaje botanico al lago Argentino [Patagonia]. An. 
Soc. Cient. Argent. 89: 179-281. pl. 1-11 + f. I-12. 1920. 
Hess, H.M. The birches. Nature Study Rev. 16: 307-316. O 1920. 
Hitchcock, A.S. The North American species of Chaetochloa. Contrib. 
Nat. Herb. 22: 155-208. f. 36-62. 1920. 
4 new combinations. 
Hitchcock, A. S. The North American species of Echinochloa. Con- 
trib. U. S. Nat. Herb. 22: 133-153. f. 25-35. 1920. 
3 new combinations. 
Hitchcock, A. S. The North American species of Isachne. Contrib. 
U.S. Nat. Herb. 22: 115-121. pl. 25-32. 1920. 
Hitchcock, A. S. The North American species of Oplismenus. Con- 
trib. U. S. Nat. Herb. 22: 123-132. f. 21-24. 1920. 
Hutchinson, J. Bocconia and Macleaya. Kew Bull. Misc. Inform. 
1920: 275. 1920. 
Includes 4 new American species of Bocconia. 
Johansen, H. El! cultivo del toronjo. Revista Agric. 16: 199-202. 
31 O 1920. [Illust.] 
Johnston, E. S. Nutrient requirement of the potato plant ai in 
sand. Cultures treated with ‘‘Type I”’ solutions. Soil. Sci. 
389-408. pl. 1 +f. I-5. 1920. : 
Kunkel, L. O., & Orton, C. R. The behavior of American potato 
varieties in the presence of the wart. U.S. Dept. Agr. Circ. 111: 
10-17. f. 2-3. O 1920. 
Kunkel, L. O., & Orton, C.R. A new host for the potato wart disease. 
U.S. Dept. Agr. Circ. 111: 17-18. f. ¢.. O 1920. 
Lankester, C. H. Orchids in Costa Rica. Orchid Rev. 28: 129-132. 
O 1920. 
Lewis, I. ¥,; & Zirkle, C. Cytology and systematic position of Porphy- 
ridium cruentum Naegeli. Am. Jour. Bot. 7: 333-339. pl. 20, 21. 
5 N 1920. 
Lyman, G. R. Potato wart in the United States. U.S. Dept. Agr. 
Circ. 813: 3-10. f. 7. O 1920. 
Matz, J. A new vascular organism in sugar cane. Jour. Dept. Agr., 
rots Rico. - Bose f- 7-0. - 1920. 
‘asmodiophora vascularum, sp. Nov: 
i J oe ae of root aes of sugar cane. Jour. Dept. 
Agr. Porto Rico. 4: 28-40. f. 6. Ja 1920. 
