The lecturer concluded his discourse by drawing attention to the limitations of human perception. Man's power of hearing was confirmed to eleven octaves of sound notes. In the case of vision the limitation was far more serious, his power of sight extending only through a single octave of those ether waves which constituted light. These ether vibrations of various frequencies could be maintained by electrical means. By pressing the stop button of the apparatus which was exhibited, ether vibrations, 50,000 millions per second, were produced. A second stop gave rise to a different vibration. Let his audience imagine a large electric organ provided with an infinite number of stops, each stop giving rise to a particular ether note. Let the lowest stop produce one vibration a second. They should then get a gigantic wave of 186,000 miles long. Let the next stop give rise to two vibrations in a second, and let each succeeding stop produce higher and higher notes. Let them imagine an unseen hand pressing the different stops in rapid succession, producing higher and higher notes. The ether note would thus rise in frequency from one vibration in a second, to tens, to hundreds, to thousands, to hundreds of thousands, to millions, to millions of millions! While the ethereal sea in which they were all immersed were being thus agitated by these multitudinous waves, they would remain entirely unaffected, for they possessed no organs of perception, to respond to these waves. As the ether note rose still higher in pitch, they would for a brief moment perceive a sensation of warmth. This would be the case when the ether vibration reached a frequency of several billions of times in a second. As the note rose still higher, their eyes would begin to be affected, a red glimmer of light being the first to make its appearance. From this point the few visible colours would be comprised within a single octave of vibration--from 400 to 800 billions in one second. As the frequency of vibration rose still higher their organs of perception would fail them completely; a great gap in their consciousness would obliterate the rest. The brief flash of light would be succeeded by unbroken darkness. How circumscribed was their knowledge? In reality they stood in the midst of a luminous ocean almost blind! The little they could see was as nothing compared to the vastness of that which they could not. But it may be said that, out of the very imperfection of his senses, man has been able, in science, to build for himself a raft of thought by which to make daring adventure on the great seas of the unknown. --_Amrita Bazar Patrika_, 24-2-1913. DR. BOSE IN LAHORE PLANT RESPONSE In his third lecture delivered, on the 25th February 1913, at the Punjab University Hall, Dr. Bose of Calcutta dealt with "Plant Response." He said:--