14 CONTENTS 



CHAPTER XXXIII „.„„ 



PAGE 



The Endocrine Glands and Their Functions _________ 666 



The Thyroid Gland, 667; The Parathyroid Glands, 670; The Supra- 

 renal Bodies, 671; The Pituitary Gland, 672; The Thymus Gland, 

 675; The Gonads and Sex Hormones, 675; The Pancreas, 677. 



CHAPTEE XXXIV 



Regeneration (By T. C. Byerly) _____________ 681 



Introduction, 681; Regenerative Capacity, 681; Protozoa, 681; Porif- 

 era, 682; Coelenterata, 682; Platyhelminthes, 683; Annelida, 684; 

 Mollusca, 686 ; Arthropoda, 686 ; Echinodermata, 686 ; Chordata, 

 687; Amphibia, 688; Reptilia, 690; Aves, 690; Mammalia, 690; 

 Basis for Regeneration, 692; Adaptability and Regeneration, 695; 

 Summary, 696, 



CHAPTER XXXV 



Biological Effects of Radiations (By Titus C. Evans) _____ 697 

 The Structure of the Atom, 697; Biological Effects of Sunlight, 700; 

 Infrared Radiation, 700 ; High Frequency Oscillations, 701 ; Effects of 

 Ultraviolet Radiation, 701 ; Roentgen Radiation, 702 ; The Funda- 



^ mental Action of Roentgen Radiation, 707; Biological Action of 

 Radium, 708; Effects of Other Radiations, 709; Summary, 710. 



CHAPTER XXXVI 



Animal Distribution (By Willis Hewatt) __-_______711 



Life Regions and Zones of the Earth, 711; Migration of Animals, 

 716; Means of Dispersal and Barriers, 717; Effects of Man Upon 

 Distribution, 718. 



CHAPTER XXXVII 



The Animal and Its Environment (By A. 0. Weese) ______ 719 



The Principal Biotic Formations, 724; Adaptation, 727; Succession, 

 727; Animal Populations, 730; Seasonal Changes, 733; Summary, 733. 



CHAPTER XXXVIII 



Animal Parasitism (By Sewell H. Hopkins) _________ 735 



Social Relations of Animals, 735; Origin of Parasitism, 736; Degrees 

 of Parasitism, 736; The Successful Parasite, 737; Means of Infec- 

 tion and Transmission, 740; Parasitism and Host Specificity, 741; 

 Parasites and the Groups in the Animal Kingdom, 742; Some Repre- 

 sentative Parasites, 747. 



CHAPTER XXXIX 



Marine Zoology -.._______-________ 766 



