242 NATURE AND LIFE. 
and fixed consistency of the surfaces, sheaths, or moulds, 
in which the cells of the new bones are to deposit and 
grow together: The method of cutting out assures the ex- 
istence of such a firm and unchanging mould by keeping a 
sheath of bone in the best conditions to procure a new 
growth of bony tissue, while that of sub-periosteal resec- 
tions expects the regeneration of the organ out of a perios- 
teum unsupported, injured, weakened, and bent under the 
influence of muscular contraction. Sédillot, who has the 
finest feeling for ancient medical art, and understands it 
thoroughly, has not left us in ignorance that Celsus had al- 
ready, a little less than a thousand years ago, proposed cut- 
ting out of the bones; but the teaching of Celsus had not 
been accepted in practice. The famous French surgeon 
rescued these precepts from oblivion, proved their useful- 
ness and importance by new arguments, explained the 
causes that warrant them, and their success, and has thus 
restored to the skillful and enlightened practice of the art 
one of the most precious means of relief for the formidable 
injuries and diseases of the bones. 
II. 
Life is a searching and expanding force which strives 
to seize upon all that comes within the range of its activity. 
We have just seen that it fills up the voids produced by 
the removal of certain organic parts; we are now about to 
see that it wins, by inverse operation, certain parts which it 
adds to living beings; for grafts are nothing less than liy- 
ing fragments pieced on to an organism already complete. 
In the vegetable graft, the grafted part does not make an 
integral portion of the single whole to which it has been 
transplanted. It does not live with the same life. It de- 
velops itself after a kind of parasitic fashion at the expense 
of the other, like misletoe on the oak; and, whether the 
grafted fragment be or be not of the same species as the 
