cost of administrative supervision should be regarded as legitimate factors in determining the reasonableness of restrictive measures. The whole problem of discrimination depends so much upon the varying conditions of different industries that an intelligent judgment of what is legitimate and what is arbitrary is possible only upon the basis of a close study of facts. There ought to be some guaranty that legislation in this respect shall proceed upon a careful and impartial survey of all relevant conditions, and in the notorious absence of such guaranties, the courts may well demand to be convinced that discriminations are not arbitrary, and that the denial of exemptions is necessary from an administrative point of view. It is a further question whether it is possible for the legislature to do full justice to the varying needs of industries by making direct provision for all cases, or whether powers of dispensation or permit must not be vested in administrative authorities. Such powers should not go beyond the province of what constitutes, properly speaking, administration. As soon as they assume the character of subsidiary regulations, there arises a constitutional difficulty in the principle that legislative powers must not be delegated. A statute of California which left it to the judgment of the labor commissioner to determine whether the inhalation of noxious gases could be prevented by the use of some mechanical contrivance, and if so, to direct its installation, was on that ground declared unconstitutional.[70] There are also, however, decisions sustaining the delegation to administrative authorities of the power to specify standards in pursuance of a general policy indicated by the legislature.[71] At present it is not clear to what extent the delegation of powers of regulation can be safely carried, nor is it probably in accordance with prevailing sentiment that it should extend to provisions that can be dealt with intelligently and effectually by legislation. IV