When they vibrate in unison with a certain color, the sensation of that color is conveyed to the brain.

Visual perceptions are the result of different wave lengths or different colors affecting the layer of rods and cones and producing more or less rapid vibrations therein.

And finally, it is color rather than form or outline that enables us to distinguish between objects; hence

It is color alone that gives us distinct visual impressions.

DISCUSSION OF DR. TALBOT'S THEORY OF VISION.

BY DAVID W. WELLS, M.D.

The axis cylinders of nerves are susceptible to mechanical, thermal, chemical, and electrical stimuli, but are not sensitive to light itself, consequently the problem before us is to determine in what way the specialized end organs of the optic nerve can transform ethereal vibrations into some one or all of these four different kinds of irritant.

The theory which Dr. Talbot presents, the adaptation or attuning of various rods and cones to vibrate in unison. with the different wave lengths from red to violet, is very fascinating, but it should be remembered that such incomprehensible velocities as "451 to 789 millions of millions" per second are possible in the realm of atomic and molecular vibration only.

The rods of the human retina are .06 mm. long and .002 mm. in diameter; and though these dimensions seem microscopic, yet compared with molecular dimensions, they are immense.

Professor Dolbear estimates the diameter of a molecule of albumen, which is made up of more than 300 times as many atoms as a molecule of water, to be 200000 mm., which is only diameter of a retinal rod.

Now the energy developed from motion depends not alone upon the velocity, but also upon the mass of the object moved.

The mass of one rod is 1,920 million times that of a mole

cule of albumen, so that it would seem impossible that velocities of light waves could be imparted to these comparatively large masses. They would be consumed in their own

heat.

The Doctor states that a "study of the minute structure of the retina seems to show that the rods and cones are capable of vibratory motion."

As the writer does not know what the evidence of this is, he is perhaps not qualified to decide that no modification of this vibratory theory could be true, but it is beyond his comprehension that visible particles of matter could vibrate in unison with light waves.

There remain three other possible modes of stimulation, thermal, chemical, and electrical. Omitting the thermal we come to the chemical, and here we have some facts.

Reference has been made to the visual purple, and the fact noted that it is absent in the fovea centralis. From this it was argued that it could not be concerned in vision, but it may have something to do with general light sense; it would certainly serve well in primitive eyes and in the peripheral parts of our own retina where definition is not needed.

Moreover, its existence suggests that there may be other substances in the cones of the macula, which may be colorless and therefore not discovered, and yet undergo a chemical change to light and thus act as a stimulant. The primitive eye is a pigment spot, and its function to distinguish light from darkness.

Evolution seizes upon and perfects existing qualities.

The reaction of an unbleached retina is alkaline, but bleaching makes it acid.

Light causes a negative variation in the electrotonic condition of the retina.

From all these facts it seems admissible to assume that vision is the result of a chemical change which irritates the end organs, either directly or through an electric agency. The facts of color vision and color blindness are easily explained on the assumption of three separate substances sen

sitive respectively to red, green, and blue light waves, as by varying combinations of these sensations the whole visible spectrum can be produced.

ELECTRICITY IN STRICTURES OF THE ESOPHAGUS.

BY DR. GEORGE B. RICE.

[Read before the Electro-Therapeutic Society, September 15, 1899.]

My first use of electricity in these conditions was prompted by an article which appeared in October, 1898, in the ElectroTherapeutic Journal on "Esophageal Stricture Cured by Electrolysis," by Dr. H. C. Bennett.

I was then treating Mrs. Y., age thirty-four, who consulted. me August 24, by the courtesy of her family physician.

The patient was pale and weak, thin in flesh almost to emaciation, despondent, bowels constipated, and she complained of difficulty in swallowing anything but liquids, and even those with increasing inability.

She gave a good family history, but her present trouble had existed for some three years, beginning without apparent cause and becoming gradually progressive. There was no pain and no sensitiveness on pressure. Examination of urine showed no marked abnormality.

After repeated attempts, a No. 6 bougie was passed into the stomach. Two strictures were found to exist, the first at the upper third, the second about an inch below this, but not exactly in line with it, the intermediate tissues being probably pouched.

At the next visit, August 30, by the aid of cocaine, a No. 7 sound was passed and an attempt made to pass No. 8. September 2, as no progress could be made, the patient was advised to go home for two weeks in the hope that better results could be obtained at the end of that time. Ignatia was prescribed and a special liquid diet of concentrated food arranged.

She came to me again September 19, slightly improved in

strength and in appearance; but there was no improvement in the stricture.

Thinking a specific lesion possible, Potassii Iodidi in fivegrain doses was prescribed, and the patient asked to report in a month. October 27, no change in condition of œsophagus. Continued Kali Iod. January 10, 1899, a gain in weight of three pounds, due probably to the special diet, but no other change noticeable. It was at this visit that the negative galvanic electrode was introduced. The size of the olive tip was equal to the No. 7 sound, and after some difficulty it became engaged in the first stricture.

A current of ten milliampères, three minutes interruptedly was used.

January 11, No. 8 passed both strictures without difficulty; January 12, 9; January 13, 10 and 11; January 14, 12 and 13; January 15, 15 and 16; January 16, 16; January 17, 17; January 18, 18, 20, and 22; January 23, 22 and 24; January 26, 22, 24, and 26; January 27, 24, 26, and 28.

On this date her physician came to my office and after a little practice could pass the sounds as well as myself. He purchased a battery with milliampère metre attached and from this time on successfully carried out the treatment at her home in a distant town.

The patient wrote me February 16, 1899, that a thirty-two bulb could be passed without effort, that she had very little difficulty in swallowing carefully prepared food, and was in good health and strength. August 8, the doctor writes me, "The patient comes to my office once a week. I can pass a No. 44 olive with ease. Her general condition has improved in an even greater proportion."

On July 22, 1898, Mr. R., age fifty-seven, consulted me for difficulty in swallowing. As in the previous case, two strictures were found in the upper third of the oesophagus, and a flexible sound No. 22 could be passed through them without difficulty. The patient was in fairly good condition. By taking considerable time he could eat most soft foods, but he felt that the trouble was slowly increasing.

No cause for the condition could be learned and the patient

He

could not tell me when he first noticed the constriction. had no pain, but at times raised blood-streaked mucus after eating. A straight-ridged sound could not be passed at this time.

After four months' treatment with flexible bougies it was found possible to pass a No. 10 olive, and a current of ten milliampères was applied for five minutes. The treatments after this were much interrupted, so that little continuous work could be done until February 11; at this time I could pass a No. 22 olive.

February 14, 22, 24, and 26; February 16, 28 and 30; February 20, 30 and 32; February 27, 30 and 32; March 8, 34 and 36; March 15, 34 and 36; March 23, 36 and 38. The patient now has no difficulty in swallowing.

He has been treated from time to time since, but there seems to be no tendency for the strictures to diminish in size, even after intervals of a month between treatments. He was last seen September 8, 1899.

At present I have a similar case under treatment, which has resisted all ordinary methods of dilatation and from the present result I have no doubt of an ultimate cure.

The first patient reported would undoubtedly have found it either necessary to submit to a doubtful surgical operation, or would have slowly starved to death but for the relief afforded by the galvanic current.

PECULIAR CASE OF ECTOPIC GESTATION.

BY CHARLES W. MORSE, M.D.

The object of this paper is to bring up this case for discussion, not that there is any special claim for the treatment, but because we believe many cases diagnosed as early abortion are, in reality, extra-uterine pregnancy.

October 20 I was called to see a woman suffering intense colicky pains in the region of the left ovary. She was thirty