in answer , the solicitor-general and the fiscal of the city of manila contend that : ( 1 ) the act was passed in the valid exercise of the police power of the state , which exercise is authorized in the constitution in the interest of national economic survival ; ( 2 ) the act has only one subject embraced in the title ; ( 3 ) no treaty or international obligations are infringed ; ( 4 ) as regards hereditary succession , only the form is affected but the value of the property is not impaired , and the institution of inheritance is only of statutory origin .