Note 29 — THE INDIVIDUAL ORGANISM WITH REGARD TO FORM AND METABOLISM
Reading edition
Great caution must be taken in attributing any specific morphogenetic part to differently coloured or constructed materials, which may be observed in the egg-protoplasm in certain cases. They may play such a part, but in other cases they certainly do not (see Lyon, Arch. Entw. Mech. 23, 1907). The final decision always depends on experiment.