A more thorough explanation:

EX DEFECTU SANGUINIS

Ex defectu sanguinis is a Latin term that means "from failure of blood" or "for want of issue." It is used in historical contexts to refer to situations where someone did not have children or heirs to pass on their legacy.

One example of ex defectu sanguinis is the case of Queen Elizabeth I of England. She was known as the "Virgin Queen" because she never married or had children, and therefore had no direct heirs to inherit the throne after her death.

Another example is the Roman Emperor Augustus, who had no biological children and had to adopt his stepson Tiberius as his heir.

These examples illustrate the concept of ex defectu sanguinis because both Queen Elizabeth I and Emperor Augustus did not have any biological children to pass on their legacy. This lack of heirs created uncertainty and instability in their respective lines of succession.