504. Combination by selection.

504.     Combination by selection.

There can be a valid claim to a mere collocation of separate integers none of which interact1, or of successive processes, or steps in a process, which are directed to different qualities of the article to be manufactured2. In such cases, however, it is prima facie sufficient to invalidate the claim that each integer, or part of the process, is old when taken by itself3; the claim can be valid only if invention was involved in selecting the best integers or process steps to put together4, and