"Recent demonstrations show that every mixture of species and kind, even where partly successful means a reversion to the original standards within the third or fourth generation in plants, flowers, fruits and in animals."
It's worthy of note that this is completely wrong. Speciation events resulting from cross pollination are not extraordinary in plants. One of the most common landscape plants in the Southwest; the Golden Barrel cactus (Echinocactus grusonii) is the result of one such union.
Since none of the JW arguments against evolution have ever been original, I would hazard a guess that their opposition probably parallels the origin and development of the modern creation movement itself.
They quote from Henry Morris in the book Creation, so it seems pretty obvious that they were reading this stuff at the time.