Page:An introduction to physiological and systematical botany (1st edition).djvu/96

66 in the autumn, when, seemingly from the increasing cold, they become benumbed; and he explains it by supposing a greater degree of electricity in the air at the former season. Dr. Brown's hypothesis, of their irritability being as it were accumulated during winter, offers a much better solution, either with respect to the animal or vegetable constitution. For the same reason, it is necessary to apply warmth very slowly and carefully to persons frozen, or even chilled only, by a more than usual degree of cold, which renders them more susceptible of heat, and a temperate diet and very moderate stimulants are most safe and useful to the unexhausted constitutions of children. The same principle accounts for the occasional flowing of the sap in autumn after a slight frost. Such a premature cold increases the sensibility of the plant to any warmth that may follow, and produces, in a degree, the same state of its constitution as exists after the longer and severer cold of winter. Let me be allowed a further illustration from the animal kingdom. Every body conversant with labouring cattle must have observed how much sooner they are