a different
manner; it may tax visible property only, and not tax securities for
payment of money; it may allow deductions for indebtedness, or not allow
them. All such regulations, and those of like character, so long as they
proceed within reasonable limits and general usage, are within the
discretion of the State Legislature, * * *"[1049] A State may adjust
its taxing system in such a way as to favor certain industries or forms
of industry,[1050] and may tax different types of taxpayers differently,
despite the fact that they compete.[1051] It does not follow that
because "some degree of inequality from the nature of things must be
permitted, gross inequality must also be allowed."[1052] Classification
may not be arbitrary; it must be based on a real and substantial
difference,[1053] but the difference need not be great or
conspicuous;[1054] but there must be no discrimination in favor of one
as against another of the same class.[1055] Also, discriminations of an
unusual character are scrutinized with especial care.[1056] A gross
sales tax graduated at increasing rates with the volume of sales,[1057]
a heavier license tax on each unit in a chain of stores where the owner
has stores located in more than one county,[1058] and a gross receipts
tax levied on corporations operating taxicabs, but not on
individuals,[1059] have been held to be repugnant to the equal
protection clause. But it is not the function of the Court to consider
the propriety or justness of the tax, to seek for the motives and
criticize the public policy which prompted the adoption of the
statute.[1060] If the evident intent and general operation of the tax
legislation is to adjust the burden with a fair and reasonable degree of
equality, the constitutional requirement is satisfied.[1061] One not
within the class claimed to be discriminated against cannot raise the
question of constitutionality of a statute on the ground that it denies
equal protection of the law.[1062] If a tax applies to a class which may
be separately taxed, those within the class may not complain because the
class might have been more aptly defined, nor because others, not of the
class, are taxed improperly.[1063]

Foreign Corporations

The equal protection clause does not require identical taxes upon all
foreign and domestic corporations in every case.[1064] In 1886, a
Pennsylvania corporation previously licensed to do business in New York
challenged an increased annual lice