126 THE NATURE-STUDY OF PLANTS 
one of the Herb Roberts, he will perhaps mistake it 
for an insect and leave it alone altogether instead of 
eating it as he might do if he thought it was a seed. 
Thus the likeness to an insect, especially in 
combination with the threads, may be of more or less 
use and protection according to the taste of the 
creature that comes across it, for the insectivorous ones 
may carry off the seed only to drop it again on finding 
out the mistake, after perhaps a struggle with the 
threads, while those that do not like insects will not 
make any attempt to eat it, although the threads 
may still secure its being carried off unconsciously. 
One cannot, however, tell what birds think, and 
one has to be very patient indeed in order to find out 
what they do; speculation and supposition are, or 
at any rate can be, harmless enough, but like guesses 
and theories they are valuable to science only in so 
far as they arouse curiosity and stimulate research, 
and I am therefore glad to be able to say that there 
are a few more or less remarkable ways in which I 
know from my own observation that these threads 
really are of great use. 
I have been interested for some time in the part 
played by Ants in dispersal, and I once caught a 
black one * in my garden dragging about a seed of the 
Herb Robert by the threads, which had got entangled 
in its tiny legs; on another occasion I watched a large 
Garden Snail} unconsciously pick up one of them, by 
the threads sticking to it; as it crawled along the 
whole thing was worked by its movements on to its 
body. At first it did not seem to mind at ali, but after 
about ten minutes the seed got to a more sensitive 
spot, and the snail began to sway its body slowly 
* Donisthorpea nigra. } Helix aspersa. 
