CONTENTS XV 



Page 

 CHAPTER XVIII 



Protozoa and Disease 88 



Pathogenic protozoa — Malarial parasite. 



PART III 

 Metazoa in General 



CHAPTER XIX 



Metazoa ^^ 



Differentiation — Division of labor— Somatic and germ cells — Potential 

 immortality of germ cells. 



CHAPTER XX 



Tissues ^° 



Definition — Epithelia — Supporting and connective tissues — Muscular tissues 

 — Nervous tissues. 



CHAPTER XXI 



Organs and Systems 104 



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

 of the body. 



CHAPTER XXII 



Reproduction in the Metazoa 107 



Methods of reproduction in metazoa — Sexual reproduction — Uniparental 

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

 sis. 



CHAPTER XXIII 



Origin of the Sex Cells 109 



Gametogenesis — Spermatogenesis — Oogenesis — Comparison and contrast 

 between spermatogenesis and oogenesis — Division of labor between the germ 

 cells — Variations in gametogenesis. 



CHAPTER XXIV 



Fertilization H^ 



Steps in fertilization — Chromosome reduction — Significance of synapsis. 



CHAPTER XXV 



Embryogeny 11^ 



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

 embryogeny — Germ layers — Coelom. 



PART IV 

 Metazoan Phyla 



CHAPTER XXVI 



Sponges 1^9 



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

 ton—Histology — Metabolism — Behavior — Reproduction — Uses of sponges 

 — Cultiration of sponges — Relations to other animals. 



