as portrayed in pictures, memory tests, requiring the child to run errands, and tests of æsthetic sense as shown by the selection of the prettiest profile from among a number of outlined women's faces printed on a large card. For all these he devised substitutes that a blind child could comprehend, such as requiring the child to recognize the objects in a basket filled with such things as a doll, spool, spoon, baby's shoe, cent, key, pocket knife, button, and a watch.

Equipped with his adapted system, he

produce the desired results, and that a blind child, though lacking vision, was more advanced in some respects than a seeing-child. It was found that a sevenyear old blind child can repeat a sentence that a seeing-child cannot repeat until he is eight.

"The records of fifty applications of the tests do no more than establish a working basis", Mr. Irwin said. "When we have records of three or four hundred tests, we shall know pretty near how much an average, normal blind child

have our facts thoroughly verified, however, we shall not be able positively to assert to what degree a blind child is normal or to what degree feeble-minded.

"It is an accepted fact that a seeingperson with the mentality of a normal twelve-year-old child can earn a living. and we assume that a blind child of the same mental age can be made self-supporting. Once we are able positively to determine a blind child's mental age, we shall be able to segregate those of low mentality in schools and institutions, as is done with seeing-children. Although there are now no special schools for the mentally defective blind, when the need of such institutions is recognized, they will be provided by the State, or otherwise. The tests will also be most valuable in classifying the adult blind, who now are thrown upon the world indiscriminately.

"The tests will effect a great saving of both money and labor in educational work. It is useless to try to give a person with a seven-year-old mind book. learning, or to teach how to read by raised letters, because such a person would be reading without the mind. Such a person, however, can be trained to do many things that will be useful to himself and to those who are charged with his care. Then there are those

of higher mentality who may be taught to be partially self-supporting, and a great many who may be. educated to a degree that will make them not only self-supporting but also useful members of society. These must not be retarded by the mentally defective, who number ten per cent of the pupils in the blind departments of our public schools.

Since it has become known that Mr. Irwin has succeeded in adapting the Binet tests to the blind, trained psychologists who have had experience with the Binet system have offered their aid in collecting clinical data. Miss Elizabeth S. Kite, of the extension department of the Training School at Vineland, New Jersey, has undertaken clinical work in Eastern New York, Eastern Pennsylvania, and New Jersey. Miss Catherine Matthews, formerly Binet tester for the State of Utah, and now a graduate student in psychology at Pittsburgh University, has arranged to examine the children at the Western Pennsylvania Institute for the Blind. Mr. S. C. Kohse, who formerly was employed by the United States immigration bureau to detect and test mentally defective immigrants at Ellis Island, and who now is head of the vocational guidance department of the city of Chicago, will test the blind children in the Chicago public schools.

Expert clinical psychologists of several institutions for the blind, from Montana to the Atlantic Coast, have written Mr. Irwin for information and charts. Correspondence is being exchanged and by the time this article is published, it is probable the Binet-Irwin tests for the blind will also be in use in Cincinnati, Columbus, St. Louis, and in blind schools in many States. Only one requirement is imposed by Mr. Irwin in allowing the use of his system, and that is a complete detailed report of each case. By spring, he hopes to have records of three or four hundred scientifically accurate tests, from which absolutely to correlate the mentality of blind children from three to twelve years of age.

B

OTANISTS have long wanted to make use of the X-ray in their studies of plants; but

until recently they have been unable to do so to any great extent, because they had no apparatus capable of doing the work properly and easily. But a recent invention by W. D. Coolidge, a scientist whose experiments with the X-ray have brought him severe and permanent physical injury, promises to meet the needs of botanists; so at last it seems that this means

THE STRUCTURE OF A CHERRY BLOSSOM Such immensely useful and interesting pictures may now be taken easily with the X-ray.

By

BLAND

EDWARDS

CHERRY PITS IN THE
MAKING

The new method enables scientists to study such phenomena in living speci

mens.

of research which has been so helpful in other fields, may now be used generally in attacking botanical problems.

The difficulty which is overcome by the Coolidge invention is that of getting instruments which can be so regulated that they will not blot out with their strong rays the delicate details of flowers and other botanical specimens. The older Roentgen tubes could not be adjusted in any way; and a tube which would do for one subject would be out of the question as a means of taking the next picture. The new Coolidge tube permits of such a wide variation in the purposes for which the same tube may be used, that it is possible to secure photographs of flowers, insects, and metal objects in consecutive order, with no change in the apparatus used except to vary the amount of current entering the tube.

The amount of current entering the vacuum tube determines the strength of the resulting X-rays and their penetrating power. When the electric current

bringing out delicate shadows of petals. and stamens, and showing young fruit forming at the base of the pistils. When making these phantom pictures of flowers, an exposure of more than onetenth of a second is seldom made, and the intensity of rays is reduced by admitting less electricity to the vacuum tube.

To make good photographs of flowers, leaves, and delicate botanical specimens requires a perfect adjustment of the apparatus and accurate judgment of the length of exposure; and yet when the proper amount of time the photographic plate needs for a perfect picture has once been determined, other botanical specimens may be photographed with almost mechanical certainty. Everyday photography is many times more difficult than X-ray work when the Coolidge tube is used; for while the amateur photographer has to work with whatever light

he may happen to have, it is possible with this new method of X-ray work always to vary the amount of light so as to accommodate the subject to be photographed.

The uses to which the Coolidge invention may be adapted in botanical work are well shown in the accompanying photographs. The pictures clearly show the work of insects, the photographs of insects in a fern leaf being especially illustrative of the ease with which life is observed within vegetable matter. Another photograph showing cherries about half developed, clearly indicates the formation of cherry pits. In all of the photographs showing flowers or blossoms, the petals are plainly but delicately visible. The pictures represent only the average work of the new vacuum tube, and were not selected with particular regard to special excellence.