154 THE NATURE-STUDY OF PLANTS 
like a hundred and fifty species which are not British. 
which are never found in the United Kingdom even 
apparently wild, and about which I know nothing 
whatever that is worth recording. 
I must now hark back for a few minutes to the 
seven factors of life. 
In this chapter and its predecessor I have ignored 
not only respiration and nutrition, but also growth, 
because there was nothing of special interest to add 
to what I had said already in Chapter VII. 
With regard to Protection, what is true of the 
Herb Robert is also, broadly speaking, true of its 
near relatives, although they do not appear as a rule 
to be quite so free from fungal and other foes, The 
glandular hairs seem to be of some pretty weighty 
importance in this respect, not only upon the leaves 
and stems, but also upon the sepals and the bill, 
protecting the pollen grains and ovules from the 
unwelcome visits of crawling insects, and the bill 
of some of the other species from being attacked by 
green fly, and spoilt for its important work of 
throwing the seeds. 
Passing on to the fifth factor, the minimum resting 
period of the seed in my own limited observations 
shows no startling disparity, for the thirty-nine days 
of the Meadow Cranesbill compared with the eleven 
of the shingle variety of the Herb Robert cannot be 
allowed to count for much: the difference amounts 
only to four weeks, and I am acquainted with genera 
of other families containing some species whose 
seeds germinate in a few days and others that lie over 
until the next spring. Moreover, the difference in 
time in seeds taken from the same plant or even from 
the same fruit, is often a great deal more than a month, 
