The propositions of Lamarckism are mentioned.
(i) Growth of Organs: The organism can grow and nourish the organs under the influence of its own vital energy on demand.
(ii) Formation of new organs on the demand of the environment: Changes in the body depend on the environment. Changes in the environment can cause changes in the nature and physical properties of organisms. Organisms change their organs and produce new organs in a changing environment.
(iii) Use and disuse of organs: The organs which the organism uses are active and nourished. Organs that are not used become inactive and ineffective.
(iv) Inheritance of Acquired Traits: The traits acquired by an organism during its life cycle are heritable.