Charak Samhita
यथास्वेनोष्मणा पाकं शारीरा यान्ति धातवः। स्रोतसा च यथास्वेन धातुः पुष्यति धातुतः ॥३९॥
Normally, the dhatus of the body get metabolised (being acted upon) by their own ushmas or dhatvagnis (transforming enzymes in the tissue elements).
english translation
yathAsvenoSmaNA pAkaM zArIrA yAnti dhAtavaH। srotasA ca yathAsvena dhAtuH puSyati dhAtutaH ॥39॥
hk transliteration by Sanscript