DEVELOPMENTAL MECHANICS. 183 



the parts affected ; the formation of bones in connective tissue 

 that has been subjected to mechanical impact ("Reit-" and 

 " Exercierknochen ") ; occasional progressive ossifications like 

 leontiasis ossea after a single injury; further, the formation of 

 giant cells around dead or dying parts (around foreign bodies), 

 around bones which are no longer supplied with nutriment, or 

 which have become disarticulated, the formation of blisters 

 under skin which has been subjected to repeated pressure or 

 displacement, the formation of the placenta materna on any 

 part of the peritoneum in extra-uterine pregnancy, the forma- 

 tion of new capillaries from those already existing in conse- 

 quence of an increased demand for nutrition, even when this 

 demand is occasioned by the presence of a body foreign to the 

 particular region (metastatic tumor), together with an increase 

 in size in the afferent and efferent vessels of the region, etc. 



The fact that transplanted pieces of skin, like artificial 

 noses, gradually acquire connections with the sensory path- 

 ways, indicates that the sensory nerves continue to send out 

 processes in all directions till every region is supplied from 

 one, or normally from two sensory branches ; this is evidence, 

 at the same time, of a peculiar touch which the parts supplied 

 with sensory nerves keep with one another or with the sensory 

 nerves of neighboring parts. 



The ends of broken bones which are not bound together and 

 hence movable on each other, gradually develop a joint with 

 the circumjacent connective tissue. Since the normal joints 

 are laid down and developed without any movement of the 

 kind, this pseudarthrosis corresponds only to \hzfurtlier devel- 

 opment of an already formed normal joint in adaptation to an 

 individual requirement. 



Peculiar properties of life are evinced furthermore by the 

 hypertrophy of connective tissue and young epiphysial cartilage 

 or bone in stoppage-hyperaemia, whereas, in contradistinction 

 to this, the specifically functional portions of glands, muscles, 

 and of the central nervous system, are injured by such hyper- 

 aemia ; further, the tendency of like parts to grow together in 

 synophthalmia, etc. Many authors will be inclined to include 

 here the formation and retention of bones in places protected 



