Write a short note on Lamarckism.

(N/A) Lamarck,in his book 'Philosophic Zoologique' $(1809)$,proposed that the evolution of life forms occurred due to the use and disuse of organs.
He provided the example of giraffes,which initially did not have long necks.
Due to the scarcity of surface vegetation,they had to stretch their necks to reach leaves on tall trees.
They adapted to this situation through the elongation of their necks.
By passing this acquired character to succeeding generations over many years,they eventually acquired long necks.
This theory,known as Lamarckism,is no longer accepted in modern biology.
August Weismann provided the greatest opposition to his theory of the inheritance of acquired characters and proposed the theory of the continuity of germplasm in $1892$.