[1] Part of a series of works by Darwin related to his theory of natural selection, the book is a study of carnivorous plants with specific attention paid to the adaptations that allow them to live in difficult conditions.[3] Darwin tried several methods to stimulate the plants into activating their trap mechanisms, including feeding them meat and glass, blowing on them and prodding them with hair.[3] He also discovered that while some plants have distinct trap-like structures, others produce sticky fluids to ensnare their prey and concluded that this was an example of natural selection pressure resulting in various methods for food capture.From his initial observations in 1860 of Drosera rotundifolia, the common sundew, Darwin developed a series of experiments ultimately establishing how "excellently adapted" these plants are to catching insects (p. 3).Darwin then turns his attention to other varieties of insectivorous plants and makes comparisons, noting that in some cases different parts of the leaf are used for digestion and others for absorption of decayed matter (p. 330–331).