43 
a fair size he should dosome of their work. This, however, 
I do not believe, as the three great laws of nature I named 
at first will keep things right. 
The destructive forces mentioned are, however, not all. 
How do we know? The answer is fairly simple. All 
shell-fish destroyed by birds or fishes will have the shells 
parted with broken to fragments. The birds either break 
up large specimens before eating them, or swallow the small 
ones whole, when the gizzard crushes them. Fishes crush 
them with the strong teeth they possess in their throats, 
but in addition to this, thousands of tons of whole shells 
are washed up by the sea, the fish having been destroyed 
by lower organisms such as the star-fish, whelks, &c., 
which feed upon them. | 
If we allowed the cockle-beds to rest, what would be 
the result? Nature would either increase her destructive 
powers, or the average individual growth would be re- 
tarded, and though there might be found a few larger 
forms which had survived the influence of the destructive 
forces to some extent, there wouid be no appreciable 
increase. to compensate for the enormous loss. As well 
might a farmer refuse to milk his cow for a week, so that 
she would have plenty of milk at the end of the time. 
The more man takes, the more room he leaves, and the 
more will grow to full size. Of course, 1 am arguing from 
the condition of things on these extensive banks. Laws 
