276 Colour and the Struggle for Life 
his classical paper. Such an arrangement is inconvenient, and I have 
followed Wallace in keeping the two categories distinct. 
The visible colours of animals are far more commonly adapted for 
Protective Resemblance than for any other purpose. The concealment 
of animals by their colours, shapes and attitudes, must have been well 
known from the period at which human beings first began to take an 
intelligent interest in Nature. An interesting early record is that of 
Samuel Felton, who (Dec. 2, 1763) figured and gave some account 
of an Acridian (Phyllotettia) from Jamaica. Of this insect he says 
Aas thorax is like a leaf that is raised perpendicularly from the 
dy.” 
Both Protective and Aggressive Resemblances were appreciated 
and clearly explained by Erasmus Darwin in 1794: “The colours of 
many animals seem adapted to their purposes of concealing them- 
selves either to avoid danger, or to spring upon their prey*.” 
Protective Resemblance of a very marked and beautiful kind is 
found in certain plants, inhabitants of desert areas. Examples ob- 
served by Burchell almost exactly a hundred years ago have already 
been mentioned on p. 273. In addition to the resemblance to stones 
Burchell observed, although he did not publish the fact, a South 
African plant concealed by its likeness to the dung of birds’. The 
observation is recorded in one of the manuscript journals kept by the 
great explorer during his journey. I owe the opportunity of studying 
it to the kindness of Mr Francis A. Burchell of the Rhodes University 
College, Grahamstown. The following account is given under the 
date July 5, 1812, when Burchell was at the Makkwarin River, about 
half-way between the Kuruman River and Litakun the old capital of 
the Bachapins (Bechuanas): “I found a curious little Crassula (not 
in flower) so snow white, that I should never has [have] distinguished 
it from the white limestones....... It was an inch high and a little 
branchy....... and was at first mistaken for the dung of birds of the 
passerine order. I have often had occasion to remark that in stony 
place[s] there grow many small succulent plants and abound insects 
(chiefly Grylli) which have exactly the same color as the ground and 
must for ever escape observation unless a person sit on the ground 
and observe very attentively.” 
1 Phil. Trans. Roy. Soc. Vol. trv. Tab. vi. p. 55. 
2 Zoonomia, Vol. 1. p. 509, London, 1794. 
3 Sir William Thiselton-Dyer has suggested the same method of concealment (Annals of 
Botany, Vol. xx. p. 123). Referring to Anacampseros papyracea, figured on plate 1x., the 
author says of its adaptive resemblance: ‘‘ At the risk of suggesting one perhaps somewhat 
far-fetched, I must confess that the aspect of the plant always calls to my mind the 
dejecta of some bird, and the more so owing to the whitening of the branches towards the 
tips’? (loc. eit. p. 126). The student of insects, who is so familiar with this very form of 
protective resemblance in larvae, and even perfect insects, will not be inclined to 
consider the suggestion far-fetched. 
