Occasionally, the terms of the offer and the circumstances of the transaction show that the offeror stipulates for notice of acceptance as well as for performance. If the offeror requires communication of acceptance as well as the performance of an act, no contract exists unless such communication of acceptance is made.1 If A offers to subscribe to a railway which is to be built, and requires acceptance of his offer in a certain time, as well as completion of the railway before such subscription is to be binding, A's offer lapses if not accepted within the time specified.2 Where A offered to allow B to use part of A's realty for a party wall, and promised to pay one-half of the cost of such wall when a building was erected on A's lot, and B did not accept this offer, but built the wall, two years later, without A's knowledge, no contract existed.3 An offer by a wife that she and her husband woud pay his stepdaughter, her daughter, for services in the family, made in his presence, though possibly not to his knowledge, is not accepted by the rendition of such services, unless the husband knew that the daughter continued her services in reliance on the promise.4