[20] Mr. Partridge in Todd's `Cyclopaedia of Anatomy
and Physiology,' vol. ii. p. 227.

[21] `La Physionomie,' par G. Lavater, tom. iv. 1820, p. 274. On the
number of the facial muscles, see vol. iv. pp. 209-211.

[22] " `Mimik und Physiognomik,' 1867, s. 91.

Finally, I must have the pleasure of expressing my obligations to
Mr. Rejlander for the trouble which he has taken in photographing for me
various expressions and gestures. I am also indebted to Herr Kindermann,
of Hamburg, for the loan of some excellent negatives of crying infants;
and to Dr. Wallich for a charming one of a smiling girl.
I have already expressed my obligations to Dr. Duchenne for generously
permitting me to have some of his large photographs copied and reduced.
All these photographs have been printed by the Heliotype process,
and the accuracy of the copy is thus guaranteed. These plates are
referred to by Roman numerals.

I am also greatly indebted to Mr. T. W. Wood for the extreme
pains which he has taken in drawing from life the expressions
of various animals. A distinguished artist, Mr. Riviere,
has had the kindness to give me two drawings of dogs--one in a
hostile and the other in a humble and caressing frame of mind.
Mr. A. May has also given me two similar sketches of dogs.
Mr. Cooper has taken much care in cutting the blocks.
Some of the photographs and drawings, namely, those by Mr. May,
and those by Mr. Wolf of the Cynopithecus, were first reproduced
by Mr. Cooper on wood by means of photography, and then engraved: