244 NATURE AND LIFE. 
reproduction by grafting not the whole periosteum, but 
merely the cells which compose the rudimentary layer ad- 
hering to that membrane, and which are the true producers 
of the elaboration of bone. Goujon has brought about the 
production of bone by grafting marrow. ‘The insertion of 
a few medullary cells beneath a dog’s skin, for instance, 
caused the development of a small bone at the spot ina few 
mouths. Surgeons at one time hoped to gain some adyan- 
tage from these facts in the artificial renovation of the bony 
parts. Some of them affirm that they have even made 
new noses; but it is now clearly proved that noses pro- 
cured by grafting with periosteum or with marrow have 
an insuperable tendency to be reabsorbed, and to disappear 
after a longer or shorter time, on account of the unfavorable 
conditions, with regard to nutrition, in which they exist. 
With no vascular or nerve connections, they are lke for- 
eign bodies in the place where they are developed. 
We may class with the grafting of bones those experi- 
ments, still in course of execution, in which Magitot and 
Legros are engaged, relating to the grafting of teeth. The 
teeth grow out of a little sac called the dental follicle, in 
which are distinguished the organ of the ivory, or bulb, and 
the organ devoted to the growth of the enamel. By graft- 
ing upon a full-grown dog a complete follicle taken from a 
dog just born, these experimenters have noted the regular 
development of the germ and the production of a complete 
tooth. The organ of the enamel, grafted by itself, did not 
retain life; the germ of the ivory, on the contrary, occa- 
sioned a formation of regularivory. Again, when the follicle, 
grafted in its entirety, was injured during the experiment, 
whether by accident or purposely, the appearance of a sort 
of bony tumor was noticed. These extremely interesting in- 
vestigations allow us to hope that we may be able at some 
time to produce, in clearly-defined conditions, the physio- 
logical replacement of teeth removed. It is proper to re- 

