MENTAL DEVELOPMENT IN ANIMALS. 
With Locat ILLUSTRATIONS (LANTERN SLIDES). 
By HON. A. NORTON, M.L.C. 
Read before the Royal Society of Queensland, 4th Oct., 1906. 
As I walked round what, in domestic language I 
understand is technically called the “drying ground ” 
at my own home, a few months ago, a small bird suddenly 
fluttered down beside me from a bushy shrub, and then, 
with every symptom of fear, it continued to flutter along 
the ground as though its wing was broken. In a moment 
there flashed through my mind the remembrance of a 
time when the world was young ; a time when I discussed, 
with companions of about my own age, this device which 
many birds practice in order to lure away from their nests 
the unwelcome human bipeds who they do not wish to 
interfere with their young. How had birds learnt this 
trick ¢ we asked ourselves wonderingly. When we 
sought for an explanation from an older boy, he said, 
« Why, it’s instinct, don’t you know?” A still older 
boy and more learned, told us patronisingly that it was 
“a hereditary practice which had come to them through 
their parents from a long lineage of parents’ parents.” 
With such explanations we had to be content, for we couid 
get no other; but neither of them settled the question, 
and we continued still to wonder where or how the birds 
had acquired the trick. In after years, as I wandered 
through the country, sometimes alone, often with com- 
panions who gave less attention to such subjects than 
we boys had done, I looked for some better explanation 
of the birds’ sagacity. “Instinct”? was not sufficient ; 
for although instinct explains much, there is an obvious 
