1470
THE NEW ZEALAND GAZETTE.
[No. 43

sight of the complex colours of the heap of wool, the candidate finds it difficult to select a skein resembling the sample in a collection where all the particular colours seem to differ from each other, and in consequence declares immediately that he can find none resembling the specimen. He is then told that an absolute resemblance is not demanded, and that no one asks impossibilities, that time is limited, many are waiting, &c. But there are people who—from natural slowness, from being unaccustomed to such business, from fear of making mistakes, especially if they have been previously examined and been suspected of colour-blindness, or from many other motives—proceed with the greatest caution. They do not even wish to touch the wool; or they search, select, and replace with the greatest care all the possible skeins without finding one corresponding with the sample, or that they wish to place beside it. Here, then, are two cases—on the one hand, too much action with the fingers, without result; on the other, too little action. The Examiner is forced to interfere in both cases

(a.) In the case of too much manual action, without corresponding practical result, the Examiner must be careful that the eye and hand of the candidate act simultaneously for the accomplishment of the desired end.

Some people forget that the hands should be subservient to the eye in this trial, and not act independently. Thus they are often seen to fix their eyes on one side while their hands are engaged on the other. This should be corrected, so as to save time and avoid further labour. The candidate should be told to cross his hands behind his back, to step back a pace, and quietly consider all the skeins, and, as soon as his eye has met one of those for which he is looking, to extend his hand and take it. The best plan is to advise him to look first at the sample and then at the pile, and to repeat this manœuvre until his eyes find what he is looking for.

This plan generally succeeds when nervousness from over-anxiety causes his hands to tremble; but it is not always easy to induce him to keep his hands behind his back until the moment for taking the skein in question.

(b.) In cases of great caution, the trial is hastened if the Examiner come to the assistance of the candidate by holding above the pile one skein after the other and requesting him to say whether it resembles the colour of the sample or not.

In cases where any one suspected of colour-blindness has remained some time to see the trial of others, and where, as often happens, he has remarked the skeins belonging to a required shade, he may, of course, profit by it in his own trial. But this can be prevented by shuffling the skeins.

It may be regarded as an advantage of this method that it has at command a great variety of resources. We have by no means mentioned all; and yet many who have only read this description will probably reproach us with having devoted ourselves too much to details, which seem to them puerile. But we believe that those who have examined the colour-sense of a great number of persons, and acquired thereby considerable experience, will think differently.

We are convinced that time is saved by the means we have described, and a more certain result obtained; whilst a practised surgeon, who has become to a certain degree a virtuoso, will accomplish his object quicker and surer by such means than one who neglects them. Recent experience fully confirms this. All those who have familiarised themselves with this method, and have had experience with colour-blindness, and of whose competence there can be no doubt, report, without exception, that it is to be fully depended on—the most practical and the best.

An advantage of the method was shown to be that those who were to be examined could be present and see each individual tested without this interfering the least with the certainty of the result. The individual test is even hastened thereby. The colour-blind, and even the normal-eyed who are not familiar with colours, are generally rather shy about being tested, in whatever way it is done. As the method, however, is carried out, they have more confidence. The majority are even amused. The old adage holds true here, that it is easier to find fault than to do it yourself. The surgeon, who watches not only the examined, but also those around, can often see from their faces how closely the latter observe the person being tested, when he takes out the wrong colours, as also when he neglects the right ones under his eye. This gives those looking on confidence and assurance, till their turn comes, when they appear as uncertain as before they were confident. There is something attractive in the process, stimulating the interest, and not without benefit.

From this we see that our judgment of a person’s colour-sense is made not only by the material result of the examination—the character of the wool selected—but often also by the way the examined acts during the test. We should mention a very common manner of persons on trial, which in many cases is of great value in diagnosis. Often, in searching for the right colour, they suddenly seize a skein to lay it with the sample, but then notice it does not correspond, and put it back in the heap. This is very characteristic; and if the Examiner has often seen it, he can readily recognise and be assured that it is an expression of difficulty in distinguishing the difference in the colours. We frequently see this in the first test with shades of greenish-blue and bluish-green. Here it means nothing important; but it is quite the reverse, however, when it concerns the grey, or one of the confusion colours (1–5). Uncertainty and hesitation as to these colours, which the colour-blind do not distinguish from the test-colour, even when directly comparing them, is positive proof of mistake, implying defective chromatic vision of the complete colour-blind type. No doubt the form of chromatic effect which we have called incomplete colour-blindness exists in several kinds and degrees. This is not the place to further discuss our experience on this point, and for the practical purpose we have in view, it is not necessary. As we have explained, there are among this class forms of colour-blindness gradually approaching normal colour-sense. How they are distinguished has been described. We designated them as possessing feeble colour-sense.

It is, perhaps, not easy to detect these special forms by any other method, or even by our own; we therefore give the following as a means of so doing. The only way of getting at it is by determining at what distance the candidate can distinguish a small coloured surface. We have to deal, in fact, with a feeble colour-sense which does not prevent the colours from being distinguished, but only renders it difficult. We may suppose, in comparison to the normal, that the feeble colour-sense is due either to a weaker response to the stimulation of the colour-perceptive organs of the retina, or else to a stimulation of a