One of Dr. Comandon's Galvanic Experiments with Paramoecia.
Under the action of electric current the organisms perform strange evolutions.
One of the difficulties which harassed all the early efforts in micro-cinematography was the control of the light so that the subjects might not be killed by the heat generated by the concentrated rays. At first an investigation could not be continued for more than a second or two, because the microbes were killed by the heat. Seeing that the pictures were taken at the rate of sixteen per second, an intermittent lighting system in synchrony with the opening of the lens was difficult to obtain, as there was the risk that the maximum illumination might not be thrown upon the subject at the precise fraction of a second during which the lens was open. Many ingenious expedients were tested to remove this disability, but without success, until at last Dr. Comandon conceived the idea of introducing a rotary shutter, similar to that fitted to the camera itself. This was tried, the shutter being placed between the condensers and the stage on which the objects were set up. This shutter was revolved by the same mechanism as drove the camera shutter, and was so timed that the opaque sector interrupted the ray of light at the same moment as the camera shutter eclipsed the lens. In this way the microbes were protected from the heat of the light while the lens was closed, and it was possible to keep them alive and in full activity in the slide for a considerable time. Repeated experiments suggested improvements in this shutter, and now the scientists employ one in which there are two or three opaque sectors of equal area spaced equidistantly, so that only a flash of light is thrown upon the microbes at the instant of exposure. Still further to lessen the evils of the heat a water condenser has been introduced between two of the glass condensers placed near the lamp. This is a small circular vessel like a big lens. It is filled with cold water and provided with the means to remove the ill effects of bubbling when the temperature rises to boiling point. The system is very much the same as that adopted by the Lumière Brothers when they first used the electric arc for the purpose of projection and with the same object—to protect the inflammable celluloid film from the heat radiated by the light.
With this ingenious and simplified apparatus Dr. Comandon has prepared some very remarkable films which have served to introduce the picture palace patrons as well as the scientists to phases of life about which little was formerly known. When thrown upon the screen the subject in some cases is magnified as many as fifty thousand times, so that the infinitesimal organisms stand up as large as dinner plates and their movements and structure and habits can easily be followed by the eye.
When the earliest films prepared by Dr. Comandon were shown by Dr. Dastre, of the Sorbonne, to the French Academy of Sciences, it was immediately realised that this was a new and reliable means of studying bacteria, and that many questions which heretofore had proved utterly unanswerable could now be solved with ease and precision. A little later the films were introduced to the public, and although it was feared that they would prove of only fleeting interest to the man in the street they have really interested him almost as deeply as the scientists. Good films of bacteria never fail to please a picture palace audience.
At present the preparation of these films is confined to a very small band of investigators. So far as bacteriology is concerned it is expert work, but there are many applications within the reach of the average microscopist. Cinematography has been of use in spreading the knowledge of the facts of health and hygiene, and now that there are propagandist movements on these subjects the aid of the living pictures will be more than ever appreciated.