6 DEPARTMENT OF AGRICULTURE BULLETINS 26-50. 



Department Bulletin No. 36 — Continued. P age , 



Marketing the highest grades 18 



How competition among buyers affects the primary market 19 



Purchase of cotton by general merchants 23 



Fluctuations of prices in primary markets 24 



The influence of staple on price in Oklahoma 26 



Selling cotton in the seed 28 



Marketing "bolly" and "gathered" cotton 31 



Summary 35 



Department Bulletin No. 37. — Nitrogenous Fertilizers Obtainable in 

 the United States. 



Introduction 1 



Sodium nitrate 2 



Production and consumption of sodium nitrate 2 



Sulphate of ammonia 4 



Artificial nitrates 7 



Calcium cyanamide 8 



Tankage and dried blood 9 



Resume" 11 



Department Bulletin No. 38. — Seed Selection of Egyptian Cotton. 



Importance of keeping the stock pure. 1 



The Egyptian type of cotton : 2 



Plant-breeding work in Arizona 3 



How the farmer may keep his seed pure 4 



What the growers' associations should undertake 5 



What the Department of Agriculture can do 6 



Summary 6 



Literature which may be consulted 7 



Department Bulletin No. 39. — Experiments with Wheat. Oats, and 

 Barley in South Dakota. 



Importance of the cereal 1 



Need for improvement 2 



Climatic conditions 2 



Soil conditions 5 



History of the cooperative experiments 6 



Experiments with wheat 7 



Experiments with oats 19 



Experiments with barley 28 



Improvement of the grain crops , 36 



Summary 37 



Department Bulletin No. 40. — The Mosaic Disease op Tobacco. 



Introduction 1 



Appearance of affected plants 2 



Local and general manifestations of the disease 7 



The mosaic of tobacco probably distinct from pokeweed mosaic 15 



Incubation period of the disease 16 



Distribution of virus in diseased plants 18 



Dissemination of virus from the point of inoculation 19 



Duration of the disease in affected plants 20 



Excision experiments with diseased plants 22 



Some properties of the vims of the disease 22 



Root inoculation with the disease 24 



Soil infection with disease 24 



