[motion picture] Introduces the endocrine system, indicates the better known glands, and the effects of the gland secretions. Highlights the difficulties involved in studying the endocrine system in man and states that the system in other vertebrates is much better known. Points out that invertebrates and plants also have chemical coordination to coordinate or regulate their activities. A normal pea plant is shown and is contrasted with a plant treated with a growth hormone. Roosters are used to show the effects of one endocrine gland secretion on the growth and characteristics of a vertebrate. Describes the modern methods of research using invertebrates.