XXIV CONTENTS 



3.4 Is Pathological Porphyrin Formation Due to Deranged 

 Breakdown of Hemoglobin? 593 



3.4.1 Introduction 593 



3.4.2 Porphyrin in Hemolytic Diseases 593 



3.4.3 Porphyrin in Liver Disea.ses and Porphyria 594 



3.4.4 Porphyrin in I^ead Intoxication 596 



3.4.5 Porphyrin Formation l)y Aromatic Amino Com- 

 pounds 596 



3.4.6 Porphyrin Formation by Hemoglobin Breakdown . 598 



3.4.7 Porphyrin Formation from Other Hematin Com- 

 pounds 599 



3.5 Pharmacology and Toxicology of Porphyrins 599 



3.5.1 Photosensitization 599 



3.5.2 Other Toxic Actions 600 



3.5.3 Physiologic Action 601 



XIII. Formation of Hemoglobin and Synthesis of Porphyrins in 



the Animal Body 603 



1 Introduction 603 



2 Some Hematologic Data 603 



2.1 Development of the Red Cell 604 



2.2 Quantitative Hematologic Data 605 



3 Requirements for Hemoglobin Synthesis in the Animal Body 607 



3.1 Introduction 607 



3.2 Building Stones of Hemoglobin 608 



3.2.1 Iron 608 



3.2.2 The Porphyrin Nucleus 608 



3.2.3 Globin 610 



3.3 Factors Necessary for Hemopoiesis 611 



2.3.1 Antipernicious Anemia Principle and Folic Acid. . . 611 



3.3.2 Vitamins 613 



3.3.3 Minerals 617 



3.4 Control of Hemopoiesis by Endocrine Factors 620 



4 Absorption of Iron and Its Incorporation in the Hemoglobin Mole- 

 cule 621 



4.1 Iron Requirements 621 



4.2 Absorption of Iron from the Gastrointestinal Tract 621 



4.3 Incorporation of Iron in the Hemoglobin Molecule 622 



5 Relations between Hemoglol)in Formation, Hemoglobin Concentra- 

 tion in the Blood, and Hemoglobin Destruction 624 



5.1 Introduction 624 



5.2 Influence of O.vygen Tension and Anoxia of the Bone Marrow 



on Hemopoiesis 625 



5.3 Direct Relations between Hemoglobin Breakdown and Hemo- 

 poiesis 625 



6 Synthesis of Respiratory Enzymes 627 



7 Synthesis of Porjihyrins by tlie Living Cell 628 



7.1 Porphyrins as Intermediates and By-Product.s of Hemoglobin 

 Synthesis " 628 



7.2 Porphyrin Formation in the Embryo • 630 



