Causes for Divorce.—
1. Impotency.
2. Adultery.
3. Wilful desertion for more than one year.
4. Wilful neglect of husband to provide for wife.
5. Habitual drunkenness.
6. Conviction for felony.
7. Cruel treatment.
8. Permanent insanity of defendant.
To maintain an action for the last cause the plaintiff must prove that defendant has been adjudged insane at least five years before the beginning of action and that the insanity is incurable.