CONTENTS xi 



CHAPTER XVII 



Protozoa in General 78 



Classification — Mastigophora — Sarcodina — Sporozoa — Infusoria — General 

 facts — Sexual reproduction in protozoa. 



CHAPTER XVIII 



Protozoa and Disease 87 



Pathogenic protozoa — Malarial parasite. 



PART III 

 Metazoa in General 



CHAPTER XIX 



Metazoa 93 



Differentiation — Division of labor — Somatic and germ cells. 



CHAPTER XX 



Tissues 96 



Definition — Epithelia — Supporting and connective tissues — Muscular tissues 

 — Nervous tissues. 



CHAPTER XXI 



Organs and Systems 102 



Definitions — Systems — Organs belonging to different systems — Other parts 

 of the body. 



CHAPTER XXII 



Reproduction in the Metazoa 105 



Methods of reproduction in metazoa — Sexual reproduction — Uniparental 

 reproduction — Types of fertilization — Oviparity and viviparity — Metagene- 

 sis. 



CHAPTER XXIII 



Origin of the Sex Cells 107 



Gametogenesis — Spermatogenesis — Oogenesis — Comparison and contrast 

 between spermatogenesis and oogenesis — Division of labor between the germ 

 cells — Variations in gametogenesis. 



CHAPTER XXIV 



Fertilization 112 



Steps in fertilization — Chromosome reduction — Significanc^e of synapsis. 



CHAPTER XXV 



Embryogeny 110 



Types of egg cells — Forms of cleavage — Steps in embryogeny — Variations in 

 embryogeny — Germ layers — Coelom. 



PART IV 



Metazoan Phyla 



CHAPTER XXVI 



Sponges 127 



Relationship of sponges — Classification — Structure — Canal systems — Skele- 



