368 tvEPolJts oJ; the sTate op sciekci:. 



Virchow's scheme. The division (jrerj in Virchow's scheme includes 

 both the light and neutral of the Committee's scheme. In Virchow's 

 scheme pure blue and grey are subdivisions of a larger division blue. 



Standard glasses for use in the Pigmentation Meter, and representing 

 the central colours of the four divisions in the Committee's scheme, may 

 be obtained from Mr. Lovibond. 



l^HY8IOLOC4ICAL MEASUREMENTS. 



In making survey tests the observer must bear in mind the fact that 

 the success of the process presupposes the goodwill of the subject, and 

 he must consider in each case the possibility of ' malingering ' on the 

 part of the subject. 



VISION. 



I. — The test of visual acuity seems both the m.ost important and the 

 most easily applied of all visual tests. It is desirable that the method 

 used should be applicable to subjects who have not learned to read. 

 Cohn's modification of Snellen's E test is therefore recommended as one 

 which meets this requirement, and which has been employed with satis- 

 factory results on uneducated children and adults. Of the several forms 

 in which this test has been used the one in which the test E is presented 

 slone through a window in a screen is recommended.' 



The test-card should be held vertically in strong diffused daylight 

 at the zero point of a scale of metres marked on the ground. The back- 

 ground on which the test-card appears should be a dull surface, and 

 there should be no bright light (such as that from the sky) falling directly 

 upon the eyes of the subject. 



The subject should be brought up to a point on the metre scale at 

 which the test E is clearly visible to liim and be instructed to turn 

 his E (pasted oil board) into same position as the test E exposed. This 

 should be repeated five times by subject in his first position, and five 

 times at each point of the scale successively one metre further from the 

 test E. If at any position the subject makes more than one error 

 (which he fails to correct on being informed of it) the previous position 

 (one metre less distant) may be taken as the measure of his visual 

 acuity. If lie makes one error only in the series of five tests five 

 further tests should be made at the same position. If he again makes 

 one error (i.e., two errors in ten tests) this position may be taken as the 

 measure of his visual acuity. The visual acuity will then be expressed 

 simply in terms of the number of metres between the test E and the 

 position of the subject when he ju&t satisfies the test. 



The subject should be tested without glasses or any other artificial 

 aid to vision. 



coLODii-Yisio:r. 



tl. — Holmgren's wools are so convenient a form of test that they 

 are to be preferred to the more refined methods that have been devised. 

 This method can be relied upon to reveal the commonest forms of 



' The cards may be obtained fron; Glaisher, 57 Wigmore Street, London, W. 



