104 THE BUTTERFLIES OF NEW ENGLAND. 



the primitive condition and have the potency within themselves under tiie 

 proper conditions of forming another animal of the same species. As 

 embryology is purely a science of cells, the student should not be satisfied 

 until he can trace cell by cell the cycle of development from ovary 

 cell through the egg cell and back to ovary cell again — the embryo- 

 logical cycle. A three-fold division might quite properly be made of 

 Embryology. Oogenesis, treating of the development of the egg from the 

 ovary cells ; Ovarigenesis, completing the cycle and treating of the forma- 

 tion of the essential elements of the ovary ; and third, the great subject of 

 Oro-anoo-eny, which deals with the main portion of the science. 



