The registrar general shall certify all extracts which may be granted by him from the registers or records deposited or to be deposited in the said office, and made receivable in evidence by virtue of the provisions herein contained, by causing them to be sealed or stamped with the seal of the office; and all extracts purporting to be stamped with the seal of the said office shall be received in evidence in all civil cases, instead of the production of the original registers or records containing such entries, subject nevertheless to the provisions herein-after contained.