that responses were almost invariably obtained under the conditions stated over distances amount to from a few inches to over 20 feet. Terry was far more sensitive than A. This condition still persists, but beginning some weeks ago, Terry began to amplify his response by stretching out his neck, opening his mouth wide and shaking his head as if trying to expel some undesirable obstruction or object from his throat. At times this action has persisted for perhaps as much as ten seconds after being started and occasionally has thereafter been repeated several times immediately following the first effort without having again been spoken to in the meantime. At first it seemed to me that it represented merely a nervous start at an unexpected sound, but later it appeared as if the human voice produced an actual physical effect upon the bird's throat or some mechanism or process in it. It was soon noted that response was more certain with low tones than with high and this naturally suggested that it might be a resonance effect in the bird's syrinx in which that organ responds to vibrations of the human voice of selected frequencies with sufficient intensity to cause a certain feeling of local irritation. This does not seem at all impossible when we recall the experience which, I suppose most of us have had, of feeling in ones back the vibrations of the voice of a person whose back was against the same object, such, for example as the back of a hard bench. Once or twice I have persisted in repeating Terry's name to him when he might be sitting anywhere--on my back, head or 20 feet away, and have had him show what certainly looked like acute discomfort. I have had him thus, when sitting on my shoulder, shake small particles of saliva (I suppose) out on to my face. It will be seen that there are a number of interesting lines of inter- possible relationships hinging upon this observation which might be well worth while running down, but these are only notes and I + See notes of