260 
A TEXT-BOOK OF BOTANY 
certain plants belonging to an adjacent continent may 
often be explained in this way. 
154. Dispersal by animals.—Only a few illustrations 
of this very large subject can be given. Water-birds are 
Fie 257.— Akene 
of Spanish nee- 
dles with barbed 
appendages.— Af- 
ter KERNER. 
altogether 537 in number; and yet the viscid mud 
was all contained in a breakfast cup!’ 
Water-birds are generally high and 
great carriers of seeds, which are con- 
tained in the mud clinging to their feet 
and legs. This mud from the borders of 
ponds is usually completely filled with 
seeds of various plants. One has no con- 
ception of the number until it is actually 
computed. The following extract from 
Darwin’s Origin of Species illustrates this 
point: 
“T took, in February, three tablespoonfuls of 
mud from three different points beneath the water, 
on the edge of a little pond. 
The mud when dried weighed 
only 6% ounces; I kept it cov- 
ered up in my study for six 
weeks, pulling up and counting 
each plant as it grew; the plants 
were of many kinds, and were 
strong fliers, and the seeds may be trans- 
ported thus to the margins of distant 
ponds and lakes, and so become very 
widely dispersed. 
In many cases seeds or fruits or heads 
develop grappling appendages of various 
kinds, forming the various burs, which 
lay hold of animals brushing past; and 
so the seeds are dispersed. Common 
beggar - ticks with 
barbed appendages. 
—After Beau. 
illustrations of 
fruits with grappling appendages are Spanish needles 
