120 A. M. PATERSON. 



In conclusion, I wish to express my deep indebtedness to Professor 

 Milnes Marshall, for much advice and encouragement during the 

 prosecution of the above researches, and for his kind assistance 

 in the preparation of the present memoir. 



EXPLANATION OF PLATES VII. and VIII. 



Illustrating Dr. Paterson's paper " On the Fate of the Muscle-Plate, 

 and the Development of the Spinal Nerves and Limb Plexuses in 

 Birds and Mammals." 



Fig. 1. Semi-diagrammatic view of transverse section through the 

 trunk of a Chick embryo at the end of the third day. 

 Both spinal nerve (N.), with its roots and ganglion (Sp. g.) 

 and muscle-plate (m. p.) are shown. The spinal cord, 

 notochord (No.), aorta (Ao.), and cardinal vein (C.V.) are 

 also indicated. The muscle-plate is just entering the body 

 wall. The section is taken between the limbs. 



Fig. 2. View showing the same structures in an embryo of three days 

 in the region of the fore limb. 



Fig. 3. From an embryo of three days six hours old, showing the 

 growth of the muscle-plate (m. p.) and spinal nerve (iV.) 

 in the trunk between the limbs. 



Fig. 4. From the same embryo in the region of the fore limb. 



Fig. 5. From an embryo aged three days fifteen hours, showing the 

 further growth of the muscle-plate (m.p.) and nerve (N.) 

 in the trunk between the limbs. 



Fig. 6. Shows the same structures in the region of the fore limb. 



Fig. 7. From an embryo aged four days, with the muscle-plate pre- 

 senting growing points at the two ends, and the nerve 

 dividing in the body wall into a ragged bundle. The 

 formation of the superior primary division (s.) of the 

 nerve and the cord to join the sympathetic (sy.) are also 

 seen. 



Fig. 8. From the same embryo, through the fore limb, showing the 

 relative position of the muscle-plate and nerve. The nerve 

 is seen dividing in the limb into a sheaf of branches. 



