374 
ERRATU M. 
p. 70 line 14 from the bottom: 
for: — the growth retardation curve for an intensity 1. 
read: — the growth retardation curve for an intensity 4. 
line 13 from the bottom: 
for: — the growth retardation curve for an intensity 4. 
read: —- the growth retardation curve for an intensity 1. 
