To this fact another stands immediately opposed; we can, namely, extract the colouring part of plants, and, as it were, exhibit it apart, while the organisation does not on this account appear to suffer at all. The colours of flowers may be extracted by spirits of wine, and tinge it; the petals meanwhile becoming white.
There are various modes of acting on flowers and their juices by re-agents. This has been done by Boyle in many experiments. Roses are bleached by sulphur, and may be restored to their first state by other acids; roses are turned green by the smoke of tobacco.
[LII.]
WORMS, INSECTS, FISHES.
With regard to creatures belonging to the lower degrees of organisation, we may first observe that worms, which live in the earth and remain in darkness and cold moisture, are imperfectly negatively coloured; worms bred in warm moisture and darkness are colourless; light seems expressly necessary to the definite exhibition of colour.