Section 68. A corporation owning a railroad connecting with another railroad, both of which are wholly constructed, or a corporation owning a railroad leasing, operating or controlling another railroad, may acquire, hold, sell and, upon such terms and to such an extent as may be authorized by a vote at a meeting called therefor, may guarantee the bonds or notes of such other railroad, whether such other railroad is located within or without this commonwealth; provided, that such bonds or notes are issued in conformity with law.