Later printings of The Wizard of Oz saw more than just changes in color plates; the color printing used throughout the text was also affected. A prime example can be seen in these two images.
The first is from an early Bobbs-Merrill printing, and the second is from a later Donohue printing. The Bobbs-Merrill pages are printed in a darker green ink than was originally used, making the text more difficult to read — but at least the entire image is there.
Donohue was a cheaper reprint house that leased the plates for the book, and turned out less expensive editions. One of their ways of saving money was to minimize the use of color throughout the book — one of the most unique features of the original edition! By dropping the green out of this text illustration, the image no longer makes any sense. Personally, I think they were cheating their customers; perhaps they should have been prevented from turning out such unattractive editions of this book!