Lord Bacon was not only a philosopher, but he was a biologist, as appears from the following: "As for living creatures, it is certain that their vital spirits are a substance compounded of an airy and flamy matter, and although air and flame being free will not mingle, yet bound in by a body that hath some fixing, will." Now and then the inventor of deduction reasons by analogy. He says: "As snow and ice holpen, and their cold activated by nitre or salt, will turn water into ice, so it may be it will turn wood or stiff clay into stone." Bacon seems to have been a believer in the transmutation of metals, and solemnly gives a formula for changing silver or copper into gold. He also believed in the transmutation of plants, and had arrived at such a height in entomology that he informed the world that "insects have no blood." It is claimed that he was a great observer, and as evidence of this he recorded the wonderful fact that "tobacco cut and dried by the fire loses weight;" that "bears in the winter wax fat in sleep, though they eat nothing;" that "tortoises have no bones;" that "there is a kind of stone, if ground and put in water where cattle drink, the cows will give more milk;" that "it is hard to cure a hurt in a Frenchman's head, but easy in his leg; that it is hard to cure a hurt in an Englishman's leg, but easy in his head;" that "wounds made with brass weapons are easier to cure than those made with iron;" that "lead will multiply and increase, as in statues buried in the ground;" and that "the rainbow touching anything causeth a sweet smell." Bacon seems also to have turned his attention to ornithology, and says that "eggs laid in the full of the moon breed better birds," and that "you can make swallows white by putting ointment on the eggs before they are hatched." He also informs us "that witches cannot hurt kings as easily as they can common people;" that "perfumes dry and strengthen the brain;" that "any one in the moment of triumph can be injured by another who casts an envious eye, and the injury is greatest when the envious glance comes from the oblique eye." Lord Bacon also turned his attention to medicine, and he states that "bracelets made of snakes are good for curing cramps;" that the "skin of a wolf might cure the colic, because a wolf has great digestion;" that "eating the roasted brains of hens and hares strengthens the memory;" that "if a woman about to become a mother eats a good many quinces and considerable coriander seed, the child will be ingenious," and that "the moss which groweth on the skull of an unburied dead man is good for staunching blood." He expresses doubt, however, "as to whether you can cure a wound by putting ointment on the weapon that caused the wound, instead of on the wound itself."