658 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
As can be seen, the V's and the V, ’s change in time for two 
reasons: because the physical quantities are changing and be- 
cause prices are changing. Having taken the wage rate as 
numeraire, the (V.15) show that each rate of change of these 
variables comes out as an algebraic sum of the rate of popula- 
tion growth, the rate of change of per-capita demand and the 
rate of increase of productivity (the latter with the negative 
sien). 
2. Similarly, the dynamic movements of employment in the 
various sectors emerge as follows: 
(V.16) 
Ef) = M elg+riept 
Ex?) =N (= +e+r) el@tri-e,,)8 , 
1=1, 2, … x(t)). 
where (3): 
M=a,;(t co 6) a, (2 - 0) — X(t co 0), 
N=a, (t- 0a, (t-0—X,(r 8 
In words, employment in each sector ¢ moves through time at 
a rate of change equal to the rate of population growth plus the 
rate of increase in per-capita demand for commodity i, minus 
the rate of increase of productivity in the sector. 
(°) The E;(t) and E,;(t) have been expressed here in terms of men per 
anit of time. For example, if the unit of time is one vear. thev would 
be expressed in terms of man-years; so that: 
S[E;(t)- E,. +)1 
= o and) 
10] Pasinetti - pag. 88