394 



The Living Plant 



But the most perfect transportation by water is found in those 

 cases where seeds are adapted expressly to this method, which 

 requires some kind of a float, and a power to resist decay for a 

 considerable time. Thus in the African Lotus, or Nelumbium 

 (figure 164), the great top-shaped and air-filled receptacle, well 

 known from its conventionalized use in the art of the East, forms 

 a very effective float for the seeds which are dropped here and 



Fig. 164. — The floating receptacle of Nelumbium, 

 showing a part of the seeds. 



Fig. 165.— The seed of 

 a water-Hly, with its 

 flotation bladder. 

 (Copied from Gray) . 



there as it goes. In some Water-lilies, the float is an air-filled 

 bladder formed by a loose seed coat around each single seed 

 (figure 165) ; and in other commoner kinds the float is a swollen 

 wall of the ovary. In the Cocoanut the great air-filled husk is a 

 development of the ovary, and so perfect a flotation device that 

 this plant forms the chief one of the palms that rise in the tropic 

 isles throughout the seven seas. So perfect, by the way, is the 

 power of this husk to resist decay in the water, that a cordage, 

 called coir, is made therefrom for special use where resistance to 

 decay in salt water is particularly needed. And by analogous 

 methods other seeds as well have been carried over vast reaches of 

 ocean. 



6. Carriage by Animals. — Most ubiquitous of all of the moving 



