Castoreum Castoreum Castoreum is a yellowish exudate from the castor sacs of the mature North American beaver ("Castor canadensis") and the European beaver ("Castor fiber"). Beavers use castoreum in combination with urine to scent mark their territory. Both beaver sexes have a pair of castor sacs and a pair of anal glands, located in two cavities under the skin between the pelvis and the base of the tail. The castor sacs are not true glands (endocrine or exocrine) on a cellular level, hence references to these structures as preputial glands, castor glands, or scent glands are misnomers. It is used as
Cybernetics: Or Control and Communication in the Animal and the Machine derived from Maltz's work. "Cybernetics" became a surprise bestseller and was widely read beyond the technical audience that Wiener had expected. In response he wrote "The Human Use of Human Beings" in which he further explored the social and psychological implications in a format more suited to the non-technical reader. In 1954, Marie Neurath produced a children's book "Machines which seem to Think" , which introduced the concepts of "Cybernetics", control systems and negative feedback in an accessible format. Cybernetics: Or Control and Communication in the Animal and the Machine Cybernetics: Or Control and Communication in the Animal and the