Fig. 2. Mendel’s annotations on page 497 of his German translation of Darwin’s The Variation of Animals and Plants Under Domestication.

The sentence noted by Mendel states (in Darwin’s original English, underlining corresponding to Mendel’s underlined words): “As each unit, or group of similar units throughout the body, casts off its gemmules, and as all are contained within the smallest egg or seed, and within each spermatozoon or pollen grain, their number and minuteness must be something inconceivable”. At the bottom of the page, Mendel wrote (in English translation) “to indulge in an impression without reflection”*.