Relation between Estrum, Ovulation, Fertilisation, etc. 117 



animals where menstruation occurred, it is indicated by + , while, 

 in those in which no sanious discharge could be recognized, the 

 fact is indicated by — . 



Rbi,ationship between Estrum, Ovui<ation, Fertil- 

 ization AND Menstruation. 



