How would lamarck have explain the length of giraffe's neck

Jean-Baptise Lamarck is credited in history as the man who made leaps in modern evolutionary theory. His theory is known as the Theory of Transformation, wherein species pass on traits from one generation to the next based on the adaptations they made within their specific environments. 

In his theory he explained the length of the giraffe's neck by applying the use and disuse concept. According to Lamarck, the giraffe's neck elongated over time because of straining to reach for the leaves that are located from higher branches. Their necks need to be used to for feeding, thus the use concept applies. While penguins' have smaller wings because they do not use it for flying like other birds would prove his disuse concept. 

Though his theory seems incomplete, he explained that nature has its own tendency of aiming for perfection. Species will always find a way to adapt to their environment and these traits will continue to be passed on to generations.