“ Much of our national legislation is embodied in codes, or systematic collections of general rules, each dealing in a comprehensive way with some general subject, such as the customs internal revenue, public lands, Indians, and patents for inventions; and it is the settled rule of decision in this court that where there is subsequent legislation upon such a subject, it carries with it an implication that the general rules are not superseded, but are to be applied in its enforcement, save as the contrary clearly appears. ”

“ To illustrate, § 3232, which precedes the others and is more or less a key to their meaning, declares: 'No person shall be engaged in or carry on any trade or business hereinafter mentioned until he has paid a special tax therefor in the manner hereinafter provided.' On the other hand, the sections in chapters 1 and 2 are, with minor exceptions, so general in their terms as to leave no doubt of their applicability to taxes imposed by subsequent legislation containing no provision to the contrary. ”

“ It is the express extension of those sections to the special taxes imposed by the oleomargarin act which gives rise to the question before stated. The position taken by the defendants in error, and sustained by the district court, is, that that extension of particular sections is an implied exclusion of all others. Expressio unius est exclusio alterius. ”