1905.] 



Cord of the Macaque Monkey. 



141 



the area at the third lumbar being 1*1 times the area at the second. At the 

 fourth lumbar the increase is more rapid, namely, 1*3, but at the fifth lumbar 

 the section area is only 0'9 that at the fourth lumbar, and so on. 



Summary. 



From the examination of the cross-sections of the lumbo-sacral-coccygeal 

 cord of the Macaque monkey (Macacus sinicus), it is seen that : — 



(1) The maximum section area of the cord, of the white substance as 

 a whole, as well as of the dorsal and the ventro-lateral columns is found in 

 the fourth lumbar region. 



(2) The maximum section area of the grey substance as a whole, and of the 

 dorsal and the ventral horns, is found in the fifth lumbar region. 



(3) Reckoning the cross-sectional area of the cord as 100, the maximum 

 percentage of the white substance as a whole, and of the dorsal and the 

 ventro-lateral columns, is found in the first lumbar region. 



(4) The maximum percentage of the grey substance is reached in the first 

 coccygeal region. 



(5) Eeckoning the total area of the grey substance in each cross-section of 

 the cord as 100, the maximum percentage of the dorsal horns is found in 

 the third coccygeal region, and that of the ventral horns in the fifth lumbar 

 region. 



For the furtherance of this research on the spinal cord of the Macaque 

 monkey, a series of drawings has been made of the minute structure of the 

 grey substance, for the purpose of determining the arrangement of the cell 

 groups at the different levels of the cord. 



It has been thought advisable to deal with this portion of the research in a 

 separate paper. 



In conclusion, I desire to thank Professor Gotch for having allowed me to 

 carry out this research in the Physiological Laboratory, Oxford, and for his 

 kind advice. I also wish to express my sincere thanks to many others who 

 have assisted and encouraged me, especially to Dr. Gr. Mann, at whose 

 suggestion the work was undertaken, for his guidance and kind help ; to 

 Dr. G-. J. Burch, for his ready assistance in many ways, and to Professor 

 C. S. Sherrington (Liverpool), for his valuable criticism and suggestions. 



VOL. lxxviii. — B. 



M 



