The new flora of Krakatau demonstrates in a remarkable degree how quickly plants are able to take possession of a sterilised region even under the most unfavourable conditions. It is by the cooperation of a variety of factors that living germs, which have been carried by some agency or other to new land like Krakatau, are able to continue their existence and even to produce new plants. A large proportion of the germs which reach the new land do not survive because they fail to find ground suited to their development or because of unfavourable climatic conditions. Seeds and fruits of other plants, for which the conditions of the new habitat may be congenial, have lost the power of germination during transport either by desiccation or by excessive wetting, or they may retain the power to germinate for a short time only after falling from the tree and this has been lost in the course of their long voyage. Many of the seeds which are capable of germination and further development are destroyed by animals either before or during germination, or they may have been killed by changes in the substratum. In the early stages of the colonisation of fresh ground, the struggle with other plants for space and light may be disregarded.