Y% PHILOSOPHY OF ZOOLOGY. 
cives and cresses, depends on the displays of this repairing 
power. But the indications of its existence which have al- 
ways appeared to me the most extraordinary, are exhibited 
by trees. Ina young silver-fir, ( Pinws picea), for exam- 
ple, I have seen the central vertical shoot cut off, so that the 
tree must have ceased to increase in height, unless there had 
been some repairing power, as the lateral branches invariably 
expand in a horizontal ceciian: But one of these lateral 
branches has begun to change its position; and, by bend- 
ing itself upwards, at last assumed a vertical direction, and 
became the leading shoot and trunk of that plant, of which 
it was formerly a subordinate branch. It has sometimes 
happened, that more branches than one changed towards 
the vertical direction, and thus rivalled each other in their 
attempts to repair the loss of the original stem. 
Animals, as we have already stated, can, in many in- 
stances, protect themselves from accidents, by resistance or 
retreat. But, when wounded, this renovating power is 
often exerted in an astonishing: degree, in repairing lacerated 
muscles, cementing broken bones, closing ruptured vessels 
and. supplying the loss of extravasated juices. In_ the 
lower orders of animals, the loss of amputated parts is 
speedily supplied by the production of new organs, as takes 
place with the tails of serpents, and the claws of lobsters ; 
or the detached parts, when placed in favourable circum- 
stances, evolve themselves imto separate and independent in- 
dividuals, as is the case with the common fresh water polypus. 
It would have been easy to have multiplied examples of 
the display of this instinctive power in repairing injuries, 
were those which have been produced not sufficient to de- 
monstrate its existence, and mark the characters by which 
it is distinguished. 
4. Possessed of a Procreative Power.—Vhe power which 
we have been considering, as displayed in the arrangement 
