Ebook Second Book in Physiology and Hygiene

All cells are active workers; and each has its special work to do. The human body may be aptly compared to a community made up of multitudes of individuals. In most communities there are various classes of workers — carpenters, blacksmiths, jewellers, chemists, merchants, teachers, etc. In the body, likewise, there is a division of labor. Some cells build, others tear down. Some cells may be compared to artists, others do the work Of scavengers. Some construct solid parts, others make the various ?uids to be employed in the body or to be removed from it. Some act as sentinels, to give the body warning of danger; others defend it when attacked by the enemies of life or health. All labor together in the most perfect harmony when their work is not in any way interfered with.