Section 105. The term "contractor," as used in article two, section two hundred and three, and article three, section three hundred and two (b), shall not include a contractor engaged in an independent business, other than that of supplying laborers or assistants, in which he serves persons other than the employer in whose service the injury occurs, but shall include a sub-contractor to whom a principal contractor has sublet any part of the work which such principal contractor has undertaken.
(105 amended Mar. 29, 1972, P.L.159, No.61)