Pattern Question

[erinmoveit]

Please help me understand this:
"Proceed in stocking st, inc 1 st at each end of needle on 3rd and every row to 104 sts, then on following alt rows to 122 st. Purl 1 row"

I understand that they wane mt increase at each end of the work. What is confusing me is the 3rd and every row and then alternating rows... not making much sense to me.