In the end the red weed succumbed almost as quickly as it had
spread.  A cankering disease, due, it is believed, to the action of
certain bacteria, presently seized upon it.  Now by the action of
natural selection, all terrestrial plants have acquired a resisting
power against bacterial diseases--they never succumb without a severe
struggle, but the red weed rotted like a thing already dead.  The
fronds became bleached, and then shrivelled and brittle.  They broke
off at the least touch, and the waters that had stimulated their early
growth carried their last vestiges out to sea.