There are two other points in the membership of the Scottish Parliament which must deserve mention. The great officers of state[39] possessed _ex officio_ seats in Parliament. It was an arrangement which had much to commend it; but there was a tendency for it to become burdensome; and in 1617 an act was passed prohibiting more than eight officers of state from possessing official seats in Parliament. It was customary also, from an early period, for the eldest sons of the great nobles to be present at meetings of the Estates.[40] They were in no sense members of Parliament. They had no right either of speaking or of voting. But had circumstances been more favourable to the growth of the power of Parliament, the conception of such a training for legislative responsibility might have been rich in practical results. The composition of the Scottish Estates offers a tempting parallel to that of the German Diet after the Great Interregnum. Constitutional development ran in the two countries on somewhat similar lines: the position of the king of Scotland was often analogous to the place held by the emperor; nobles and prelates correspond to the temporal and ecclesiastical princes, and the royal burghs to the free cities, while in neither assembly were there any members like the English "knights of the shire." But there does not seem to be any ground for regarding the likeness as more than a coincidence, or for disputing the "orthodox" theory which declines to admit the existence of German influence over Scotland before the sixteenth century. Had we any definite constitutional life to record, it would be of interest to discover in what relation the three Estates stood to each other. But as to this we have almost no evidence. The first instance of the occurrence of the term the "three Estates" (_tres communitates_) in the acts belongs to the year 1357.[41] In mediæval times, the three Estates are the clergy, barons, and burgesses. When James I attempted to introduce commissioners from shires into Parliament,[42] he really contemplated the creation of an additional Estate, and after his scheme was actually carried out by James VI[43] there were three or four Estates according as the clergy were represented or not.[44] The word "Estates" is not specially appropriate, and the Estates of the realm of Scotland must not be confused with the English use of the word.