From the very beginnings of the commercial slide trade in the 1830s, preparations of unusual, exotic, or striking "one off"  objects or specimens were offered to attract the purchaser's attention and interest. These unusual objects were often sections of recent fossil discoveries, or items with some particular current, historical, or geological interest. From the early 1800s, a fascination with Ancient Egyptian Civilization became evident (which lasts to some extent to this day!), and somewhat rare slides of various materials were prepared which catered to this interest. 

There may or may not be a real connection here... the original Wallace was a famous Circus Lion of an early period (1820s-30s), and this slide (c. 1870s) of "Lioness Mrs. Wallace's Whisker Hair" was possibly made up to capitalize on that interest and the well known name.

A sensational "Sport" of the time... Lion Baiting at Warwick between Wallace and dogs, Tinker and Ball, circa 1825.

An interesting "spinthariscope on a slide", circa early 1900s

The reverse side of an unusual and rare C.M. Topping mount "Human Hair - Beard"  above (2nd from left). Following Topping's instruction to "Turn over" on the 2nd front label, we find the written detail "Beard of Thomas Beaufort, second son of John of Gaunt - buried 1428, exhumed 1772"  also in Topping's hand. (W. Rutt was an early collector, click for more information)

Silk Fibers (imaged using DIC)

Above, A selection of four "Egyptian interest" mounts, all by C.M. Topping, with slide 2nd from Left, "Sect. of Wood ~ Coffin of a Mummy" imaged below with Darkfield lighting, and showing cellular structure.