I have always found publisher's devices to be of interest. Their origins are of course derived from the early printer's devices, the best known being the anchor and dolphin of Aldus Manutius, much adapted through the ages. Others such as those of the Antwerp printer, Christopher Plantin, and the Estienne family of printers originally out of Paris, used latin phrases along with their images much like those in heraldry. Plantin used labore et constantia, while the Estienne family used noli altum sapere, sed time. Most of the major University presses have their own phrases and devices which are fairly recognizable and common to the eye, but it is the lesser known nineteenth and twentieth century publisher's devices that I find more interesting.
Having recently looked at two books at random sitting on the same shelf, I couldn't help notice the similar Latin phrase used. The folia inter folia of the MacMillan Company of Canada comes from a book published in 1934 (J. B. Priestley's English Journey) while the inter folia fructus comes from a book published in 1935 by D. Appleton-Century Company (Stephen Leacock's Mark Twain.) The image of the tree, an iconographic deep-rooted mainstay, along with the open book, another stalwart image, are also used in these devices. The MacMillan woodcut is much more rustic and reflects the Thoreau MacDonald Ryerson Press style which was perhaps the self-conceived and projected image of Canada at the time. The choice of maple leaves was a simple one.
It is unlikely that one would see the phrases, Leaves among the leaves, and Fruit among the Leaves used by publishers today, but they still hold a charm and reflect their period. The date 1933 listed on the book in the D. Appleton-Century device is the year when D. Appleton merged with The Century Publishing Company.
Both books, as stated on the copyright page, were printed in the United States of America. It seems the actual printing for MacMillan of Canada was handled by American printing companies--at least during this period. Although some publishers, mainly British, listed the name of the printer either on the reverse of the title page, or along the bottom of one of the rear free endpapers, many printers are anonymously listed in the basic phrase, Printed in the United States of America, or Printed in Canada. To see the changes in publishing from when printers were the acme of the creative process of publishing, to the present time when they are but anonymous jobbers, makes me wonder what changes are coming to publishing in the next hundred years. For someone who won't be around at that time, such anticipations may be fruitless; or perhaps I should say, non inter folia fructus(?)
addendum: Looking at another MacMillan of Canada book published in 1928 with the same woodcut publisher's device, I notice that at the bottom of the copyright page the printer is listed as The Hunter-Rose Company, Limited. A little info can be found here on this old Canadian printer/publisher.