Jones, Development of the Sympathetic. 



129 



Condition after the Metamorphosis. — By the time the tail has 

 almost disappeared, the sympathetic cord not only is completely 

 separated from its antecedent structures, but is removed dorsal- 

 ly and somewhat laterally from the aorta. In the mid-trunk 

 region, it lies as high as the upper border of the notochord 

 (Fig. 12, Sy. G. 2.), while in the preceding stage it was on a 

 level with the lower border of it. 





Fig. 12. — Transverse section through the second spinal nerve, from a toad 

 in which the tail has almost completely disappeared. Col. Sy., collateral sympa- 

 thetic. R., ramus. Sp. G. 2., ganglion second spinal nerve. Sp. N. 2., second 

 spinal nerve. Other abbreviations, same as in preceding figures. For develop- 

 ment of ramus, cf. Fig. 4. X 246. Camera lucida. Reichert, oc. 4, obj. 3. 



The ridge and the structure with which it was connected, 

 have now atrophied almost completely. Nearly all of the rami 

 communicantes have become much longer, and the collateral 

 sympathetic also is well developed (Fig. 12, Col. Sv.), while 

 the differentiation of ganglia and commissures is now almost 

 complete. 



