646 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 
28 
capital is perfectly adaptable and can be transferred to other 
processes of production, then even negative gross investments 
can take place in those sectors. 
In no case, however, as said above, can total gross invest- 
ment become negative. In other words. the inequality 
(V.7) 
2 au) + + Ain | 2:0 
must always and in any case be satisfied. 
3. The flows of the svstem 
Within each single period of time (finite or infinitesimal as 
it may be) there are flows of commodities from the production 
processes to the final sector and flows of labour services from 
the final sector to the production processes. These flows have 
been examined already in the short-run inquiry of chapter II, 
and need not be further discussed here. Within each single 
period -of time, the structure of the system is represented by 
systems (II.g) and (II.13), and we may consider these two 
systems as rewritten here. The only difference is that we must 
now add a time subscript to each single coefficient and to each 
single variable, so that we obtain a pair of those systems for 
each unit of time we are considering. And since a very spe- 
cific set of hypotheses has been made about how the coeffi- 
cients of production and of demand change as time goes on, we 
shall now at last be able to look into the whole dynamics of 
the system. In other words, after finding the solutions of the 
equations in each particular period of time, we shall be in a 
position to look at the movements of these solutions through 
time. 
As explained in chapter II, the rate of profit (nr) which ap- 
10] Pasinetti - pag. 76