I. DESCRIPTIVE AND COMPARATIVE EMBRYOLOGY 



KEY 



1 Theoretical problems and general questions 



2 Methods and techniques 



3 Para-embryological subjects 

 a General subjects 



b Reproduction 



4 Initial development 



a Primordial germ cells 



b Gametogenesis until completion 



1 Spermatogenesis, sperm 



2 Oogenesis, ovum 



3 Egg membranes 

 c Maturation 



d Ovulation and oviposition 



e Fertilization 



f Parthenogenesis 



g General subjects 



5 Cleavage 



a Cleavage 

 b Cell-lineage 



6 Further development o[ Evertebrata 

 a General investigations 



1 General subjects 



2 Complete and partial development 



3 Normal tables 

 b Embryogenesis 



1 Pre-gastrulation 



2 Gastrulation 



3 Formation of germ layers 



4 Late embryonic development 

 c Larval development 



d Development of parts of the organism 



1 Head 



2 Extremities 



3 Other parts 



e Development of organ systems and organs 

 (Cf. Key on p. 195) 



7 Further development of Chordata 

 a General investigations 



1 General subjects 



2 Complete and partial development 



3 Implantation, placentation, extra-embryonic membranes 



4 Normal tables 

 b Gastrulation 



1 Pre-gastrulation 



2 Gastrulation 



c Neurulation etc. 

 1 Neurulation 



198 



