208 
Transactions of the Royal Society of South Africa. 
So marked are some of the modifications for the protection of the post- 
larval stages of fishes that one may well be led to believe that this is the 
stage that requires special protection. Out of the millions of young which 
a single pair of fish produce in their life-time, it only requires two to repro- 
duce the species in order to maintain it at its normal quantity, and it is 
sometimes believed that the necessary elimination of the surplus takes place 
in the larval stages ; but it is not impossible that the most critical period in 
the life of a fish is the post-larval, and this, as is evident, has an important 
practical bearing on the question of artificial propagation. 
