6 DEPARTMENT OF AGRICULTURE, BULS. 326-350. 



Department Bulletin No. 341. — -Farm Management Practice op Chester 

 County, Pa.: Page. 



Objects of study 1 



Application to Chester County agriculture 3 



Territory surveyed 4 



Types of farming 13 



Magnitude of business 55 



Tenant farms 68 



Quality of business 73 



Farm organization 81 



Depreciation of dairy cows 93 



Depreciation of work horses 95 



Value of manure 96 



Index 99 



Department Bulletin No. 342. — The Present Status of the Pasteuriza- 

 tion op Milk: 



Meaning of the term "Pasteurization " • 1 



Value of pasteurization 1 



Extent of pasteurization in the United States 3 



Methods of pasteurization 4 



Advantages of low-temperature pasteurization 5 



Temperature and methods most suitable for pasteurization 6 



Supervision of the process y 7 



Handling pasteurized milk 8 



Cost of pasteurizing milk 9 



Bacteria which survive pasteurization : 9 



Modern theories of pasteurization 13 



The necessity for pasteurization 15 



References to literature lo 



Department Bulletin No. 343. — Ground-wood Pulp. Part I — The 

 Grinding- op Cooked and Uncooked Spruce. Part II — Substitutes 

 for Spruce in the Manufacture of Ground-wood Pulp. 



Object of the bulletin. 1 



Present status of the ground-wood industry 2 



Present methods of manufacture 6 



Part I— 



Equipment used in the experiments 7 



Methods employed in experimental tests 9 



Effect of preliminary treatment of spruce 11 



The effect of variable grinding conditions 17 



Part II— 



Experimental and commercial tests on various woods 34 



Appendix A 67 



Appendix B 151 



Department Bulletin No. 344. — Studies on the Biology of the Arizona 

 Wild Cotton Weevil: 



Introduction 1 



Distribution of the Thurberia plant and weevil - 2 



Habitat of plant and weevil 3 



Seasonal activity of plant and weevil in nature . 6 



Emergence of weevils 8 



Relative attraction of cotton and Thurberia for weevils 10 



Life-history studies 13 



Parasites and predatory enemies of the weevil 23 



Department Bulletin No. 345. — Notes on the Preovlposition Period 

 of the House Fly, Musca Domestica L: 



Introduction 1 



The-preoviposition period : 3 



Copulation „ 12 



Longevity '. 12 



Summary 13 



Literature cited . » 13 



Publications of the U.S. Department of Agriculture relating to house 



flies and other household insects 14 



