48 Biological Conditions 



Nephrodiumcalcaratum(BL)Hook. Nephrodium cucullatum (Bl.) 



Bak. 

 Nephrodium flaccidum Hook. Nephrolepis exaltata Schott 



Onychium auratum Kaulf. Pteris aquilina L. 



Pteris longifolia L. Pteris marginata Bory 



The plants in this list, as the notes appended to the list of the whole 

 flora show, are also characterised by a wide distribution. Some are 

 cosmopolitan and, as in the case of Lycopodiwm ccrnuum, Pteris 

 aquilina, and others, are met with in all parts of the world. Others 

 are spread over the tropics of the Old World (Emilia sonchifolia, 

 Vernonia cinerea, Saccharum spontaneimi, etc.), occurring throughout 

 the whole of subtropical and tropical Asia or in the Malay Archipelago 

 region. Within their respective distribution-areas they belong to the 

 commonest plants and to such as grow indifferently in a great variety of 

 habitats. These constituents of the new Krakatau flora owe their 

 occurrence in the new habitat, as also their wide distribution, chiefly 

 to the efficient adaptation of their fruits and seeds to distant 

 transport. 



IV. The biological conditions on Krakatau. 



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 co- 

 operation 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. 



On the other hand, a plant which has begun to grow requires such 

 conditions as are favourable to the fertilisation of its flowers and the 



