Vertebrates 



687 



which are caught in traps, but this is dis- 

 tinctly not an automatic reflex type. 



The various tissues regenerated within the 

 tail structure are far different from its 

 original composition. The external form of 

 the tail, including its scaly covering, is fairly 



tebrae are not segmented but form a con- 

 tinuovxs tube which, because it is thin walled 

 and little calcified, has the same or greater 

 degree of flexibility as had the segmented 

 structure. The muscle mass regenerates but 

 shows little of the original segmentation and 



Fig. 243. X-rays of regenerates of the tail in Lacerta muralis. The right-hand illustration shows a 

 regenerate replacing the normal. The stimulation in this case was by cutting the ninth tail vertebra, 

 whereas the left figure was cut at the fourteenth with regeneration occurring at the breaking point of 

 the eighteenth tail vertebra. (From Slotopolsky, '21— '22.) 



completely reconstituted, but the internal 

 relations are not normal. The spinal cord 

 regenerates incompletely; the membranes 

 extend down a ratlier amorphous type of 

 tube formed of procartilage, the nervous 

 tissue itself being reduced to a thin strand 

 chiefly glial rather than neuronal. Seldom 

 are spinal ganglia formed, for the nerve 

 tnmk gives rise to no nerve roots except at 

 the anterior end of the regenerate. The ver- 



the organ has a flaccidity which is quite 

 different from the original state. Woodland 

 ('21) gave an excellent picture of this con- 

 dition in the gecko {Hemidactylus flavivir- 

 idis) . 



Limbs are shown by Egger (1888) and 

 Marcucci ('30) to have the ability to regen- 

 erate in part, but here as in the tail region 

 the skeletal elements are imperfect and, be- 

 cause of this, many of the appendages re- 



