The Compendium of Caraka 3.1.22

3.1.22

tatra prakṛtirucyate svabhāvo yaḥ, sa punarāhārauṣadhadravyāṇāṃ svābhāviko gurvādiguṇayogaḥ; tadyathā --- māṣamudgayoḥ, śūkaraiṇayośca//

Therein, natural constitution is said to be that which is intrinsic nature; it is, moreover, the natural possession of heavy and other qualities in food and medicinal substances, such as of black gram and green gram, or of domestic pig and blackbuck deer.