त्वच एवास्य रुधिरं प्रस्यन्दि त्वच उ-त्पटः ।तस्मात्तदातृण्णात्प्रैति रसो वृक्षा-दिवाहतात् ॥ २ ॥
In plain words
It's the skin the blood comes from — the skin is where it breaks through. So when you're cut, blood comes out of the wound the same way sap runs out of a tree that's been struck.
Close to the Sanskrit
From the skin alone flows this person's blood; from the skin comes the bursting-out. Therefore, from what is torn, that [blood] issues forth, like sap from a tree that has been struck.