124 Journal of Comparative Neurology and Psychology. 



marked, especially in the region of the lumbar plexus, where it 

 has reached the height of its development (Fig. lo, Rt.). The 

 angle which it makes with the horizontal plane varies in differ- 

 ent regions. Anteriorly, it extends upward and inward (Fig. 

 5, Rt.), approaching even a horizontal position in some places. 

 Following it backward, in the region where the median aorta 

 begins (Fig's. loand li, *), it assumes rather abruptly a vertical 

 position, and then immediately begins to lean outward, till, in 

 the region of the kidney, it points upward and outward (Fig. 6, 

 Rl), making an angle with the horizontal plane varying from 

 30° to 60°. 



fig, <5. — Transverse section of 18.5 mm. toad, between the sixth and sev- 

 enth spinal nerves (see Fig. lO), shovi^ing the sympathetic ridge, A*/., and the sym- 

 pathetic cord, Sy., well differentiated at the top of the ridge. Abbreviations, 

 same as in preceding figures. X 246. Camera lucida. Reichert, oc. 2, obj. 7 a. 



The sympathetic cord (Fig. 6, Sy.) is larger and more defi- 

 nite, and is lound surrounded by a membrane more frequently 

 than it is seen without one. The cord lies at the top of the 

 ridge, including in a few places the greater part of the latter. 

 The rami communicantes, at this stage, have increased in size 

 and distinctness. Besides those in connection with the fourth, 



