July 4, 1895] 



NATURE 



-00 



damage to the liigher centre seems to lower the function 

 of the whole, as if the function were diffused, and all 

 its elements were represented, in varying degrees, in ever)' 

 part. This conception is so unfamiliar that it may seem 

 inconceivable, and yet it harmonises with many of the facts of 

 subjective sensations. Moreover, in a large part of the brain, 

 local loss of tissue has only the effect of lowering function as a 

 whole. It seems to be only where the sensory impulses reach 

 the cortex, and motor impulses leave it, that the local distribu- 

 tion of function is definite, and limited damage has definite and 

 lasting results. 



The spectra perceived before epileptic fits vary widely. They 

 may be stars or sparks, spherical luminous bodies, or mere 

 flashes of light, white or coloured, still or in movement. Often 

 they are more elaborate, distinct visions of faces, persons, objects, 

 places. They may be combined with sensations from the other 

 special senses, as with hearing and smell. In one case a warn- 

 ing, constant for years, began with thumping in the chest ascend- 

 ing to the heail, where it became a beating sound. Then two 

 lights appeared, advancing nearer with a pulsating motion. 

 Suddenly these disappeared and were replaced by the figure of 

 an old woman in a red cloak, always the same, who offered the 

 patient something that had the smell of Tonquin beans, and then 

 he lost consciousness. Such warnings may be called p.sycho- 

 visual sensations. The psychical element may be verj- strong, 

 as in one woman whose fits were preceded by a sudden distinct 

 \-ision of London in ruins, the river Thames emptied to receive 

 the rubbish, and she the only survivor of the inhabitants. 



The colours seen are chiefly described as red, green, blue and 

 yellow. A yellowish red-like flame is very common. In some 

 cases red changes to green, a curious complementary relation, 

 when we consider that the sensation is due to a primary process 

 in the centre. One obtrusive fact, in these spectra and in those 

 of migraine, is the frequency with which colours extend to the 

 edge of the field of vision. In one case, each fit was preceded 

 by the appearance of a green colour occupying the lower half of 

 the field so completely that the patient said he seemed to be in 

 a field of grass. It is often said that the periphery of the retina 

 is not sensitive to colour, and that red and green are seen only in 

 the centre. But long ago, Chodin and Landolt showed that 

 colour vision extends to the periphery. The peripheral colour 

 spectra led the lecturer to make a careful examination of the 

 peripheral colour vision, especially in regard to area, to which it 

 seems to be related in a greater degree than to illumination. 



Red can be seen up to the margin of the field for white, an 

 area in 6 cm. square ; green cannot well be discerned within 

 5° of the margin, but yellow and blue can be seen up tn the 

 margin with 4 cm. square. The fields for each area from "25 to 4 

 cm. square are concentric with the fiekl for white. 



One fact was ascertained which illustrates the mutual influeiice 

 of the two visual centres. When both eyes are open the two 

 fields correspond, except in ihe outer temporal third of each 

 field. The nasal half of left field, for instance, extends to 55° 

 of the outer horizontal radius of the right field, the end 

 of which is at 90°. When both eyes are open, not only 

 is the perception of colour intensified in the part where the two 

 fields overlap, but the intensification goes on to the periphery, 

 through the part in which there is no more retinal stimulation 

 than when the right eye alone is open. Thus, in this radius, 

 red is seen in 2 cm. square at 62° with right eye alone, but 

 at 74° if the left eye is also open, although the left field 

 does not extend beyond 55". The colour is seen in 4 

 cm. square at 77"* with the right eye only, and at the margin 

 of the field only with 6 cm. s<iuare, but with both eyes open the 

 4 cm. stjuare enables the colour to be seen up to the margin, 

 instead of at 77°. There is thus greater sensitiveness in the 

 centres to colour impulses proceeding from the peripheral region, 

 where the field is single, if light from the other eye intensifies 

 their action — a striking instance of their intimate co-operation. 



The motor relations of the epileptic spectnim are instructive 

 but too complex for brief description. It is common, in one- 

 sided fits, for an object to appear at the edge of the field of vision 

 on Ihe side afterwards convulsed, and pass across, to disappear 

 at the opposite side. Its appearance, c./r., on the left is followed 

 by movement of the head towards it, Ijy the motor centres of the 

 right hemisphere, but the head then follows the movement of the 

 spectrum, by the action of the centres of the other hemisphere 

 (sometimes with a conscious sense of irresistible compulsion), and 

 then finally deviates strongly in the first direction, as the con- 

 vulsion comes on, usually with loss of consciousness. A sense 



NO. 1340, VOL. 52] 



of vertigo may accompany the deviation. The eyes move before 

 the head, and may be absolutely fixed when the head can be 

 moved by the will. These phenomena throw instructive light 

 on the relations of objective and subjective vertigo. Inhibition 

 frequently precedes the epileptic spectra, but is always general, 

 never partial, and neither the loss nor the spectrum is ever on 

 one side only. If they appear on one side, it is only to move 

 across the field, apparently as the result of the effect on the visual 

 discharge of the associated motor nature of the epileptic process. 



The visual sensations which precede the paroxysmal head- 

 aches of migraine differ very much from the warnings of 

 epilepsy. Their general character is limited, but their forms are 

 extremely varied. One has been well made known by the 

 careful study of his own sensations by Dr. Hubert Airey, 

 published in the Philosophical Transaclioits for 1870, reproduced 

 by Dr. Liveing in his classical work on megrim. (Unpublished 

 drawings by Dr. Airey, and several other series of drawings 

 were exhibited. One curious set was made by a mechanical 

 draughtsman who, from sixty to sixty-five years of age, frequently 

 experienced visual sensations, similar to those of migraine, as 

 isolated s)Tnptoms, without headache, and always depicted them 

 as objective things, related to his own figure.) In this class of 

 spectra, inhibitory loss of sight is almost invariable, but it is 

 always partial, never general as in epilepsy, and it bears a 

 definite relation to the spectrum. The phenomena are generally 

 on one side, but occasionally medial, although never central, and 

 they never correspond to one half of the field.' Even loss 

 strictly limited to the medial line, as in hemianopia due to 

 organic disease, is practically unknown, contrary to the common 

 impression. The special feature of the "discharge" is an 

 angled line of light, the "zigzag" spectrum, single or repeated, 

 sometimes in many, as it w-ere reflected, fading, lines. In 

 round or oval form it has been termed the " fortification 

 spectrum," from resemblance to the plan of a fortress devised 

 by \'auban. The angled line may be of simple bright light or 

 may present colours, red, green, blue, orange, which sometimes 

 alternate in successive segments. It often seems made up of a 

 multitude of minute brilliant points in rapid movement. \\Tien 

 a single bright line, it may be banded on each side by a very 

 narrow black line. This feature may be observed in the 

 "phosphene" produced by pressure on the eye, even in the 

 dark, when it is apparently due to a limiting line of loss of the 

 " essential light of the retina," but its presence in a central 

 spectrum raises the question whether this so-called " light of the 

 retina" is not of purely central origin. 



The central region is remarkably indisposed to discharge, but 

 prone to inhibition. A medical practitioner, a carefiil obser\-er, 

 experienced first a spot of central dimness of sight, which 

 enlarged, becoming darker in the centre and ultimately extended 

 from top to bottom of the field, occupying the middle third, 

 banded on each side by a double curve. Sometimes, when the 

 spot had reached half-way to the top and bottom of the field, 

 a bright zigzag line appeared on one side, which extended 

 upwards and downwards, as the inhibitory loss increased, 

 became brighter, but seemed to restrain the inhibition, which 

 extended no further on that side, but was, as it were, reflected 

 back and reached almost the extreme edge of the field on the 

 other side. This illustrates the occurrence of the discharge 

 secondary to inhibition, and limiting it. It is an instance of 

 the way in which all half-field relations are absent in these 

 phenomena. The common commencement is for an angled 

 sphere, or stellate spectnmi, to appear in the middle zone of one 

 half of the field, and, expanding, form an oval within which 

 vision is partially or completely lost. The edge is often coloured. 

 The angles are especially developed towards the outer side of 

 the field. Towards the centre of the field the expansion is less, 

 the angles smaller, and the spectrum breaks. Sometimes one 

 limb passes downwards, and the other towards the central point, 

 but in the latter the angles gradually cease, and the spectrum 

 never reaches the centre — an illustration of the resistance of the 

 central region to discharge. In other cases, however, the ends 

 of the bri^ken oval may pass into the other half of the field, one 

 on each side of the central point, enclosing this between them. 

 When they reach the middle zone on the other side, a second 

 star, like that from which the spectrum originated, may suddenly 

 appear for a short time as a terminal feature. These character- 

 istics show how remarkable must be the relation of the centres 

 in which their cause occurs. 



1 By " (ield " is mcaiu the area included by the bound.irj- of the conjoined 

 fields of both eyes, lo which alone the central phenomena seem related. ; 



