Plate V. 



S. 1. 



W. 1. 



S. 2. 



Via. 1. Miciopliotngraph of pollack .scale at end of second summer. 

 (Magnified 4.'i diameters.) 



C.= Centre of growth. 



C. — W. 1. = Gro\vtli of tirst year. 



C— S. 1. = Growth of first summer. 



S. 1.— W. l. = Growth of first winter. 



W. 1.— S. 2. = Growth of second summer. 



To face page 374. 



Journ Mar. Bit)l. Assoc. VI. 



