Page:Mind (New Series) Volume 12.djvu/316

 302 W. MCDOUGALL : FACTORS OF THE ATTENTION-PROCESS. of our knowledge of the facts in recent years. We can no longer regard the cord as consisting of ' centres,' i.e., of groups of nerve-cell-bodies that are the sole or principal storehouses of energy and the seats of its more or less spontaneous libera- tion and direction. We have rather to regard the cord as a complex interconnected system of nervous channels, every part of which is equally capable of setting free a certain amount of energy in response to stimulation and in propor- tion to the intensity of the stimuli, while the direction of the flow of the liberated energy is the function of the mode of interconnexion of the channels. The final step towards the adoption of this view has been rendered necessary by recent work of Prof. Verworn and his pupil, Dr. Baglioni. 1 It was formerly held that the spasms of the animal poisoned with strychnine afforded the most striking and unmistakable manifestation of the spontaneous liberation of energy in the ' motor centres ' of the cord. These observers have shown however that even in the convulsions of the strychnine- poisoned animal the continued outflow of energy from the cord by the efferent nerves is dependent upon a continued influx by the afferent nerves, chiefly those of the ' muscular sense 1 Engelmann's Archiven for 1900 and supplementary volume of same year. 2 Sir J. Burd on- Sanderson in a recent communication to the Physi- ological Society has questioned the validity of Verworii's and Baglioni's conclusion, showing that in the strychnine-poisoned animal a single stimulus may cause a series of about ten twitches of diminishing vigour, although all other afferent impulses be prevented from reaching the cord. It is not clear however that this constitutes an exception, it would seem rather to be an instance of multiple response to a single intense stimulus exactly parallel to the multiple response of the visual apparatus to a single intense stimulus which I have recently described .(Brain, Winter, 1901, p. 603).