CALLITHRIX JACCHUS, THE MARMOSET 



173 



animal docs not possess the celerity, the dexterity or the muscular power to 

 adapt itself to an extensive natural environment. Neither has it the capacity 

 to create out of its environmental conditions new coml^inations which 



FIG. 85. MARMOSET. LEVEL AT THE MIDDLE OF THE PONS VAROLII. 

 CEN, Central Gray Matter; ctt, Central Tegmental Tract; cow. Ventral Spinocerebellar Tract; lf. Lateral 

 Fillet; mcp. Middle Cerebellar Peduncle; mf. Mesial Fillet; N4, Trochlear Nerve; pd, Predorsal Bundle; 

 PL, Posterior Longitudinal Fasciculus; pn, Pontile Nuclei; pv, Pyramid; ref. Reticular Formation; scp, 

 Superior Cerebellar Peduncle; tvr, Tractus Uncinatus of Russel (Houk Bundle). (Accession No. 146. Section 

 123. Actual Size 9X5 mm.| 



would necessitate the development of a more complex motor organization. 

 Hence it lives within a limited sphere of action whose requirements demand 

 a relatively simple motor organization. 



LEVEL OF THE INFERIOR COLLICULUS (FIG. 86) 



At the level of the inferior colliculus the most significant modifica- 

 tion is the appearance of this elevation (IC), the primordial relay station 



