vertical columns, while another series of arches and uprights, darker than the general ground, appeared, intersecting the former, so as to have the dark uprights just intermediate between the bright ones of the first set. On the second occasion the pattern consisted of a very slender and delicate hoop, surrounded with a set of circles of the same size, as tangents to the centre circle and to one another. On the third occasion the whole visual area was covered with separate circles, each having within it a four-sided pattern of concave circular arcs. All these phenomena were much fainter than in the chloroform exhibition."
The accuracy of these descriptions will be readily admitted, as far as my own observations have enabled me to judge. I am, however, disposed to believe that the forms under which the spectra present themselves vary persistently in different individuals to a considerable extent.
A question now naturally arises: What are these spectra, and how are they formed?
An eminent scientific authority has suggested to me that they are possibly referable to that obscure mental process which Dr. Carpenter has termed unconscious cerebration. (See "Human Physiology.") But, allowing this to be the case, the questions put by Sir John Herschel still remain unanswered:
"Where do the patterns or their prototypes in the intellect originate?
"If it be suggested that a kaleidoscopic power of forming regular patterns, by the combination of casual elements, exists in the sensorium, how is it that we are unconscious of the power—unable to use it voluntarily—only aware of its being exerted at times in a manner in which we have actually no part but as spectators?"
I cannot help thinking that more than one of the most ancient types of symbolism upon which so much learning and ingenuity have been expended in endeavors to invest them with mystical meanings, or to trace their origin in the forms of the organic world, may have been first suggested by these hitherto-unnoticed spectra.
But besides these geometrical forms, there are others, which I must again describe in Sir John Herschel's words:
"I fancy," he writes, "that it is no very uncommon thing for persons in the dark, and with their eyes closed, to see, or seem to see, faces and landscapes. I believe I am as little visionary as most people, but the former case very frequently happens to myself. The faces present themselves voluntarily, are always shadowy and indistinct in outline, for the most part unpleasing, though not hideous, expressive of no violent emotions, and succeeding one another at short intervals of time, as if melting into each other. Sometimes ten or a dozen appear in succession, and have always, on each separate occasion, something of a general resemblance of expression, or some peculiarity of feature common to all, though very various in individual aspect and
