362 Dynamic Theory. 



cording to its age. The claws and tail plates are also reproduced, but 

 slower. l ' With crawfish under a year old all the severed limbs grow 

 again in about 70 days. " "Their eyes will also grow again, and in one 

 case two eyes came in place of one lost." ( Papillon.) 



The renewals of tissue are under the same law and process as the 

 first embryonic development of them. The epidermis, hair and nails are 

 all the same tissue. The crystalline humor of the eye is also from the 

 epidermis, and grows again after removal, in the cases of dogs and rab- 

 bits, in a few months. Cataract of the eye consists in the crystalline 

 lens becoming filled with opaque matter, and it is relieved only by the 

 removal of the lens, which has never in human subjects grown again 

 perhaps because only old people have cataract. Its place is artificially 

 supplied by very strong glasses, so that the patients can easily read 

 thereafter. The derma of the skin, the vessels, the tendons and nerves, 

 all repair their bruises and breaks. If a piece be cut out of a nerve, as 

 the sciatic, the repair begins by the nerve matter at one of the cut ends 

 forming into a grayish bunch, and pushing out along the former track of 

 the nerve till it unites with the opposite end. ' ' This bunch is made 

 up of laminated tissue and nerve tubes more slender than the original 

 tubes, but by slow degrees it enlarges, grows whiter, its fibres become 

 complete, and after a lapse of from four to six months we have a nerve 

 cord of new formation. Such a cord is reproduced even when a part of 

 the nerve six centimeters, (2.36 inches,) in length has been removed." 

 Its functions come gradually as it grows. Also nerves of different 

 function have been joined cut and crossed over to others they are not 

 naturally connected with. 



Cartilage also has been renewed in two months in dogs and rabbits, 

 in experiments of Legros. The same man also proved the renewal of 

 smooth muscle ( i. e. , involuntary muscle, as intestine ) . Fibrous mus- 

 cle is also rebuilt by fresh muscle matter. Bone is also renewed. The 

 periosteum is partly composed of a cartilaginous substance, which is 

 shown to be bone in process of formation. If this periosteum be car- 

 ried away from the bone and twisted among the tissues and muscles, it 

 will turn to bone in the anomalous shape it may happen to be left in. 

 And in case of fracture of bone this substance is furnished by the peri- 

 osteum or it may be by the core of the bone itself to form new bone 

 to fill the fractured crack and cement itself to the two ends. 



As examples of what may be called distortion of crystallization in an 

 organic body, the following from Spencer's Biology may be quoted : 

 " When the hip-joint has been dislocated, and long delay has made it 

 impossible to restore the parts to their proper places, the head of the 

 thigh-bone, imbedded in the surrounding muscles, becomes fixed in its 

 new position by attachments of fibrous tissue, which afford support 



