210 HISTORY OF BRITISH ZOOPHYTES. 
work. “That the motion of the water descends to a good 
depth I prove from those plants that grow deepest in the 
sea, because they all generally grow flat, in manner of a fan, 
and not with branches on all sides, like trees, which is so 
contrived by the Providence of nature, for that the edges of 
them do in that posture with most ease cut the water flow- 
ing to and fro; and should the flat side be objected to the 
stream, it would soon be turned edge-wise by the force of 
it, because in that state it doth least resist the motion of 
the water; whereas, did the branches of the plants grow 
round, they would be thrown backward and forward every 
tide. Nay, not only the herbaceous and woody submarine 
plants, but also the lithophyta themselves affect this manner 
of growing, as I have observed in various kinds of coral and 
por.” (Ray.) 
In forming their network, the little creatures are taught 
to give greater strength to the fabric by a few stronger 
tubes, that proceed lengthways, and a few that irregularly 
cross the fan. Ellis, in figuring Venus’s fan, has chosen a 
specimen which shows the ingenuity of the polypes m re- 
pairing the damage when one of the main stems had been 
broken through near the base. As the separation of the 
parts of the great tube was complete, and the upper part of 
