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 in a few 

 months. Surgeons at one time hoped to gain some advan- 

 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 like 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 regular ivory. 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- 



