I think it is best to quote directly from the book - Art Nouveau - "The idea was a harmonious integration of text and image, as opposed to isolated plates of scattered throughout the volume" - page 116."
While the author recognizes the power of Art Nouveau in the style of layout - this book in no means uses it. Often the artwork they take the time to explain is located on another page and is not harmonious integrated into the text. Creating a complete disconnect from the content and the art work.
Whoever did the layout and typesetting should be ashamed!