published to the world in a book called _Philosophical Zoology_, without taking any steps to test the truth of his guess. That is where Lamarck’s method and attitude as a scientific man is so greatly inferior to that of Darwin. Lamarck, sitting in his study, said animals (and plants too) must be affected by the conditions around them, so that an individual as it lives and grows becomes to a certain degree slightly changed by and adapted to those conditions. This, he said, we all see in human beings and familiar animals and plants. Now, he said, we have only to admit that the changes so acquired are (especially when both parents have been similarly changed) transmitted to the young in the process of generation, and to some degree “intensified,” in order to recognise that of necessity there is in nature a constant change and progression of living forms, consisting in a more and more elaborate “adaptation” to the conditions of life, which will be varied and lead to new adaptations as the living things spread over the earth or as geological changes occur. He cited the long neck of the giraffe as an example of what he meant. In regions where there was frequent and extensive drought, a deer-like creature would eat the lower leaves of trees when the grass was dried up and dead. It would strain and stretch its neck in reaching after the higher leaves, and the individuals thus straining and stretching would become an inch or two longer in the neck in consequence. These individuals would, said Lamarck, transmit their increased length of neck to their offspring, who again would strain and stretch after higher leaves, and get a further increase of neck-length, and so it would go on, little by little, over many thousand generations, until the neck-stretchers had become well marked and distinguished by their long necks from such of their ancestral stock as survived in other regions where, the grass being good, there was no inducement to straining and stretching the neck.