There is a canal beginning from the mouth down to the anus. Its extremity is called the anus. From this main canal various minor oncs branch out in the bodies of all living creatures.
आस्यं हि पायुपर्यन्तमन्ते स्याद् गुदसंज्ञितम्। स्रोतस्तस्मात् प्रजायन्ते सर्वस्रोतांसि देहिनाम्॥