XXVII CERATOPHYLLUM 



399 



a temperature of 80° F., the reading being usually 78^ to 79°, I 

 never found the plants in fruit, and it is only in the superheated 

 shallow waters of the swamps and back-waters that they mature 

 their fruits. 



Since Ceratophyllum even in tropical climates would probably 

 only mature its fruits in the superheated waters of shallow ponds, 

 tanks, and ditches, it follows that its dispersal by birds is confined 

 to warm regions. In the cold waters of the Siberian lakes and 

 rivers it would never mature its seeds, and could only be propagated 

 by budding. If it existed in the head-springs of the sources of a 

 river in these latitudes, it would be distributed by means of its 

 floating shoots and fragments along the length of the river basin, 

 and in the times of flood it might pass in the lower plains from 

 one river system to another. When rivers changed their courses it 

 would be left behind in the lakes and ponds and springs, and would 

 also be carried away to the new region. In this manner it would 

 in the course of ages be distributed over a continent without the 

 aid of seed, propagating itself in a vegetative fashion. 



In the case of oceanic islands, however, we have to appeal to 

 the seed. Since the fruits sink in sea-water even after prolonged 

 drying, and since a few days' immersion in sea-water, as I found, 

 kills the floating plant, we are driven to the agency of birds. The 

 fruits, which without appendages are a quarter of an inch (6 mm.) 

 in length, are too large and heavy to be carried in dry mud adhering 

 to birds. The chances of their becoming entangled in a bird's 

 feathers by means of their basal spines and terminal style seem 

 small, since they would be lying usually on the mud under the 

 water. They are quite fitted for safe transport in the stomach and 

 intestines of birds, such as is established in Chapter XXXIII for 

 Potamogeton and Sparganium in the case of ducks. As my 

 experiments show, drying for a period of three months does not 

 injure the germinating capacity of the seeds. 



Dracontomelon (Anacardiaceae) 



This is a genus accredited in the Index Kewensis with eight 

 species, of which three belong to Borneo, one to Sumatra, one to 

 Java, one to the Philippines, and two to Fiji, all the species being 

 restricted in their range. My observations were confined to 

 D. vitiense, Engler (D. sylvestre in Seemann's work), the Tarawau 

 of the Fijians, who regard it as a tree that is planted by the dead 

 in Naithombothombo, the place of departed sjDirits, according to the 



