18. When any arrest must be made according to these instructions, it must, for any case of bigamy, be made according to clause fifteen. The commissary shall issue orders entrusting the matter, as is customary, to some one of the familiars whom he has to keep in the city. Until he has familiars, for lack of them he shall entrust it to the person on whom he has most reliance, and in whose integrity he most confides. When it is necessary, but only then, he may ask for the aid of the royal officials of justice. Whenever this shall be necessary, the royal officials may seize only the person pointed out to them by the Holy Office; and they must assist him, giving their favor and aid only for such person. In order to obtain this help, the commissary needs only to ask for it in polite terms; and it may be demanded without the necessity of giving information, either written or oral, regarding the offense--and, indeed, he shall be very careful not to do so. On the contrary, if anyone should be so inconsiderate as to ask for such information, let the commissary send us a detailed account of what takes place in the matter. 19. Royal magistrates are under obligation to render this assistance, since the request therefor does not require from them any fees, alguacil, or scrivener. The magistrates are also under obligation to receive and keep any prisoner in their jails, to take good care of him, and to account for him, but without exacting therefor any prison-fees. Accordingly the commissary will, when occasion arises, notify the magistrates and request their assistance; and if necessary he will command it, under pain of excommunication and a money fine. Thus he will not be obliged to find another and special prison, and incur the expense of guards. If the rank of the person, and the condition of the prison, and the nature of the crime require a more special and secret prison, on account of the danger that the prisoner may be able to communicate his affairs to other persons, such arrangements are left to the judgment of the commissary, who is charged to see that in these arrests little outcry be made, and that all scandal be avoided.