How did Charles Darwin’s views on acquired characteristics resemble Lamarckism?

In On the Origin of Species, Charles Darwin accepted the inheritance of acquired characteristics as a contributing factor to evolution, aligning his views with Lamarckism.1

To explain this transmission, Darwin proposed a provisional hypothesis called pangenesis. He theorized that body parts shed invisible particles known as "gemmules," which traveled through the blood to the germ cells. These particles were thought to modify the germ cells to reflect changes occurring in the peripheral organs, effectively allowing an individual's life experiences or physical modifications to be passed to the next generation.1

While Darwin utilized this concept, his perspective differed from traditional Lamarckian views in specific ways. For instance, he recognized that the simple loss of a body part is not inherited, as the germ material already contains the units necessary for that part's development. Despite this, his inclusion of acquired characteristics in his broader framework created significant historical confusion regarding the distinction between his theory of natural selection and Lamarck’s doctrine.1