248 BIOLOGICAL PHYSICS 



Its position, in relation to the developing vertebrae, 

 assumes a central course, which it continues to maintain, 

 after it has ceased to perform an active functional work, 

 and is found surviving even in adult life ; it is, therefore, 

 one of those structural survivals, about which it is 

 not too much to say, that, it is conceivable, it may 

 have to do with functional revivals, physiological, or 

 pathological, such as we have claimed for the thyro- 

 glossal duct, in relation to the etiology of some cases 

 of goitre. 



Moreover, we would draw attention to the resemblance 

 of the function, we have assigned to this embryonic 

 structure, to that usually assigned to the periosteum of 

 the bones, constituting the other parts of the skeleton 

 (i.e. excepting the bones, to which the notochord conveys 

 ossific matter during its active existence), in the physio- 

 logical process involved in the formation of callus, between, 

 and around, the ends of fractured bones, during their 

 course of " knitting," and restoration to complete, if not 

 exact, continuity of texture. Here, it would seem to 

 us, that a large portion of the callus, if not all, is of 

 nervine origin, in which respect it exactly resembles the 

 ossifying material, deposited from the notochord amid 

 the centres of ossification of the individual vertebras, 

 and that it is deposited from the ruptured periosteal, 

 and fractured bone, structures, and licked into organic 

 form by the inter-penetrating and omnipresent, sympa- 

 thetic nervature. 



From this it would appear, that the systemic nervature 

 is responsible for a large proportion of the growth, and 

 nutrition, of all the structures subservient to its voluntary 

 control, and that it, therefore, seems no longer strange 

 to meet with cartilaginous, or osseous, deposits, not only 

 in immediate relationship to the proper skeleton, but 

 throughout the whole organism, wherever the systemic 

 nerve structures are distributed. 



Like neuroma, which is an accumulation, in the neuri- 

 lemmar sheaths, of the white substance of Schwann, 

 disconnected deposits, or growths, of cartilage, or 

 bone, found up and down the body, are arrested 

 osseous, and, more or less, organised, materials, due 



