142 PHOTO-MICROGRAPHS. 
malcules. One unfamiliar with the facts recorded 
would very naturally suppose that these actively 
moving organisms were little animals, as active 
movement is a characteristic associated in our 
minds with animal life. In the microscopic world, 
however, this is not a distinguishing characteristic ; 
for we not only have plants which move freely 
from place to place, but we have animals which 
are permanently located in one position. 
It seems probable that the main object of these 
“motile” forms is to secure the extensive distribu- 
tion of the species. Among flowering plants this 
is accomplished in a variety of ways, and especially 
by means of appendages which aid in the dissemi- 
nation of the seeds by the winds or by animals. 
Without this provision for their preservation, our 
little plants would be liable to become extinct, 
both because they would exhaust the nutriment 
necessary for their growth if restricted to a few 
localities, and because the animals which feed 
upon them would have too great an advantage if 
they always remained at home to be eaten. 
