THE MICROMOTOSCOPE.[17]
[17] By D. F. St. Clair.
The principles of the kinetoscope or mutoscope have been applied to the microscope, with some interesting results, by Dr. Robert L. Watkins, of New York City. The instrument, though simple, was made a success only after many experiments and failures in adjusting the objective of the microscope in a line with the right sort of light and a rapidly moving film.
The principal difficulties in making a mutoscope out of so delicate an instrument as the microscope are the light and the lens. Every electric lamp in the market, when its light has been concentrated sufficiently for photography, will, after a short time, with its heat, kill, dry up, or impair almost any kind of life in the microscopic field. The greater the magnification, the more intense the light must be and the nearer the microscope. This difficulty was often enhanced by the length of time it took to get a focus on the sensitive film, but most of the pictures taken were good, and show well the various characteristics of the action taking place in cell life, so far as it can be observed with the microscope.
A ROTIFER AS SEEN IN THE MICROMOTOSCOPE.
Whatever is to be photographed, once it is put in the field of the lens, is adjusted to a horizontal plane. Near one end of the microscope is placed an electric lantern containing a small arc light concentrated on the object. Near the other end is the box that covers the apparatus for moving the long, sensitive gelatine film. The film runs like a belt, on wheels, and passes in front of a tiny window in the box and on a direct line with the lens and light. This machinery is turned by a crank, and its ordinary capacity is about 1,600 pictures per minute. It is possible to increase it to 2,000 or 2,500, but for most purposes 1,000 or even less per minute will record every motion taking place in most cell life. Dr. Watkins found, however, after a number of trials, that he could not turn the machine fast enough to photograph the motion of the blood circulating in the web of a frog’s foot. He simply needed a larger wheel.
The advantages of mutoscopic photography to microscopy are quite evident, especially as regards the action of bacteria and blood cells. Nearly all the numerous families of bacteria have motion, many having motion that the eye cannot always follow clearly. It has already been discovered that the same kind of bacteria will act very differently under different circumstances. For instance, a flash of bright light will suddenly drive some kinds to cover. Some kinds will readily seek the negative pole of the battery. They will also seek food with avidity and reject poison with true instinct. All such phenomena can, of course, be followed with the eye, but not with the same detail in the microscopic field as in a series of clear photographs. The fact is that on account of the motion of some bacteria it has been well nigh impossible to photograph them. The books have had to depend upon the eye and hand of the draughtsman and upon vague description. This may not be of much importance either way, but as yet comparatively little is known about bacteria. It is not yet known whether they are the cause of disease, or its results, or neither. Photography, under the proper circumstances, is most needed for the investigator, and it can be only moving photography.