The second line of the third verse is "Sorrow and love flow mingled down!" sung to this musical phrase:
"Flow" is sung with a melisma (A G), giving something of a sense of movement, and since this pair of notes descends, there's even a bit of the sense of the "down" from the end of the line.
In the fourth verse, the text here is "That ["the whole realm of nature"] were a tribute far too small." Here, "too" is sung with a melisma (E F), provided a sense of degree.
The fourth verse ends with the lines "Love so amazing, so divine, / Demands my soul, my life, my all!" The first of these two lines is sung to this phrase:
"Amazing" and "divine" are both sung with melismas (G A G A and A G A, respectively), and these articulations provide a sense of degree for those "so"s.
