I just got a copy of Feynman's lectures on Physics the other week. They are very interesting. Near the end of the 4th chapter, he begins discussing conservation laws. One of the laws he gives is the conservation of baryons. I noticed early in the first volume, the lectures were published in 1960, a few years before the theory of quarks came about. Would it be off to say that, had the book been published today, this conservation law would be replaced by the conservation laws of quarks and color?