296 Royal Society. 
However, it cannot be doubted that though the colour of purple 
stuffs was primitively violet, the requirements of taste and of fashion 
led to the variation of its shades. Thus some stuffs were dyed 
twice, to give them a richer and more vivid colour—the so-called 
‘purpurea dibapha.’ The mixture:of species also contributed to 
modify the hues. 
Murex trunculus gives an almost blue shade. The fishermen of 
Port Mahon told me that it always yielded that colour, and especially 
that it would give a fixed and permanent colour. On the contrary, 
Purpura hemastoma (which they call ‘cor de fel’) was known to 
them as staining their linen very permanently and ineffaceably. 
It ought also to be recollected that when mineral colours replaced 
the animal matter of mollusks, the hue varied ; and though the term 
‘purple’ might be retained, it was easy to pass by degrees to the 
deep red which rises in the mind when we recollect the purple worn 
by cardinals. 
Perhaps also the manipulations to which the molluscan dye-stuff 
may have been subjected by the dyers, of the nature of which we know 
nothing, approximated the purple to the red, which Pliny compares 
to that of coagulated blood. 
But it remains none the less demonstrated, both by the passages 
from ancient authors and by experiment, that the primitive and 
natural colour of the purple was formerly, as now, violet. 
Hence it would appear to be requisite for a painter to consider 
the epoch when the personages who are represented clothed in purple 
drapery lived, for the hue varied with the age. The properties of 
the purple dye-stuff also render intelligible one ground of the esteem 
in which the colour was held; for, developed by the influence of 
light, it could not fade, like the red of cochineal for example, but 
must always have remained beautiful, even in the luminous and 
dazzling atmosphere of Italy and the East. 
It would be difficult, with the scanty materials we possess, to 
determine exactly the species employed by the ancients. Without 
Fig. 1. Fig. 2. 
Fig. 1. Animal with Purpura lapillus, with the pallial cavity laid open. 
1. Genital orifice. 3. Anal gland. 5. Branchie. 
2. Anus. 4, Purpurogenic organ. 6. Organ of Bojanus. 
Fig. 2. The animal simply removed from its shell. 
1. Branchie. 2. Purpurogenic organ. 3. Anal gland. 
