120 
PLANT STUDIES 
suddenly curls up and throws the seeds (see Fig. 123). The 
squirting cucumber is so named because it becomes very 
much distended with water, which is finally forcibly ejected 
along with the mass of seed. An " artillery plant " common 
in cultivation discharges its 
seeds with considerable vio- 
lence ; while the detonations 
resulting from the explosions 
of the seed-vessels of Hura 
crepitans, the " monkey's din- 
ner bell/' are often remarked 
by travelers in tropical 
forests. 
81. Dispersal of seeds by animals. Only a few illustra- 
tions can be given of this very large subject. Water birds 
are great carriers of seeds which are contained in the mud 
clinging to their feet and legs. This mud from the borders 
of ponds is usually completely filled with seeds and spores 
of various plants. One has no conception of the number 
until they are actually com- 
puted. The following ex- 
tract from Darwin's Origin 
of Species illustrates this 
point : 
FIG. 126. The fruit of carrot, showing 
the grappling appendages. After 
BEAL. 
FIG. 127. The fruit of cocklebur, showing 
the grappling appendages. After BEAL. 
"I took, in February, three 
tablespoonfuls of mud from three 
different points beneath water, 
on the edge of a little pond. This mud when dried weighed only 6f 
ounces ; I kept it covered up in my study for six months, pulling up 
and counting each plant as it grew ; the plants were of many kinds, 
and were altogether 537 in number ; and yet the viscid mud was all 
contained in a breakfast cup ! " 
Water birds are generally high and strong fliers, and the 
seeds and spores may thus be transported to the margins of 
distant ponds or lakes, and so very widely dispersed. 
In many cases seeds or fruits develop grappling append- 
