cess, due perhaps to the lack of specialists, the large expense involved, and certain limitations of the subject. The public undoubtedly is interested; the secondary schools and colleges would welcome aid of this kind and it remains for some large educational institutions to establish a micro-cinema laboratory for the production of such negatives.

The producer of such films, if he be well acquainted with the various branches of science, can devise interesting and original experiments to suit any stage of knowledge. He can vary the experiments so as to bring the pupil face to face with something which can never be illustrated by diagrams in a textbook. He can lead the pupil step by step, and the more deeply he plunges into the particular branch of science, the wider will be his scope in the portrayal of scientific phenomena by fascinating experiments.

Cinema-biology a Demonstrator of

Vital Life Factors

In

Above all, the cinematograph gives the scientist an opportunity to illustrate at will and repeatedly the results of the laboratory experiments. many colleges, in medical schools, and even in certain classes of high schools, it is important to demonstrate the living phenomena as closely as possible; sketches, wall charts, or still photographs do not show the different movements and the results of experiments; they do not show the technique of the experimenter or the accompanying reactions of the organism such as the beating of the heart, the circulation of the blood, and the acceleration of respiration.

But by means of the cinematograph the most delicate operation can be recorded and all its details reproduced with the utmost precision. At the same time this wonderful instrument will save many hours of tedious laboratory routine which could be used to far

greater advantage in original research. On the other hand, cinematography will widen the teaching power of any single experiment or demonstration, and become the greatest of all teach

ers.

When an experiment is well executed and recorded on the film, and then shown to a large audience of students, each individual can follow it precisely and in all its details. By varying the rapidity of the exposure the cinematograph can quicken or retard the movements. As is easily understood, this possibility offers great advantage for demonstration.

Each film becomes a document representing a scientific truth, and from this record any number of copies can be reproduced for the different schools and colleges of the country. The demonstration by cinematograph possesses certain marked advantages over the laboratory experiment: it reaches simultaneously and equally a greater number of spectators; it enables the teacher to demonstrate an important fact leisurely and repeatedly; it permits the student to interrogate and thus accurately crystallize his deductions from the experiment.

A cinematographic apparatus for taking and exhibiting scientific motion pictures has been installed by the Faculties of Medicine in Paris, Lyons, Bordeaux, at the Pasteur Institute in Paris and Lille, and even in certain museums. Records of the many surgical techniques and biological processes necessitated by the great war have in this way not only been visually preserved but have also been actually used for disseminating the knowledge gained.

But the auditorium and the class room should not be the only places in which to exhibit scientific motion pictures; a corporation should be established through whose agency certain scientific subjects could be exhibited to the public. Every day there are hap

penings of interest and importance in the scientific world of which the people at large have only a hazy understanding. Scientists make discoveries which illumine the dark phenomena of ordinary life; inventors create new wonders for the benefit of mankind-but about all these things the people for whose benefit the creative mind of the scientist really works, know little or nothing. Many of these subjects could be rearranged so that they would be entertaining and at the same time would give the public the kind of picture which is instructive, which demonstrates vital factors in life.

Films Showing Circulation of Blood in the Chick Embryo

My interest in this work has arisen through laboratory researches on living tissue in the department of physiology at the American Museum of Natural History. In collaboration with Mr. Alessandro Fabbri, research associate in physiology in the American Museum, who is much interested in biological cinematography, there has been prepared a microscopical film 1200 feet long, on the physiology of the heart and the circulation of the blood in the chick embryo. This work was done in the private laboratory of Mr. Fabbri,a laboratory completely equipped with all facilities for the highest grade of cinematography.

The physiology of the heart and the circulation of the blood have attracted the attention of investigators from very early times. Far back in 1616 scientists studied them. William Harvey was the first to grasp the fact that the heart acted as a force pump to drive the blood in a circle through the blood vessels and back. Since the time of Harvey, however, physiological technique has been remarkably improved. Many methods have been discovered to demonstrate the general function of the heart and vascular system. But not until cinema-microscopy attracted the

attention of modern physiologists, has it been possible publicly to demonstrate the finer details of this phenomenon.

In the film which has been made, the first scene demonstrates the necessity of carefully marking on the shell of the egg the date and hour when it is placed in the laboratory incubator, in order to obtain an embryo of known. age. A constant temperature of 103 degrees Fahrenheit is maintained.

The second illustrates how, after forty-eight hours, the egg is removed from the incubator and, after being carefully opened, is placed in a glass dish, embryo and vascular area uppermost. The vascular area, with its embryo, is now dissected from the yolk and transferred to a large culture chamber, which is sealed with a cover glass by means of hot paraffin and placed under the micro-cinematographic apparatus.

We see the entire living embryo, forty-eight hours old, demonstrating the circulation in the vascular area. The circulatory system of the young chick consists of branching tubes, the arteries coming from the heart, which is now outside of the body. Dividing into a fine network of capillaries in the vascular area, these vessels reunite into a large vein which carries the blood back to the heart at the opposite side.

The picture shows the heart as a muscular organ which rhythmically contracts, decreasing its volume, and thereby driving out the blood which has flowed into it during the period of relaxation. In mammals and birds there are two separate circulations; the two pumps are combined side by side, the right auricle and ventricle form one pump, while the left auricle and ventricle form the other.

The subject of the fourth scene is the heart of a living embryo thirtythree hours old, showing its first rhythmical activity and the course of the blood in the transparent heart cavity during contraction.

The next picture shows us a heart of a living embryo thirty-six hours old, with body still transparent enough to demonstrate the action of the heart valves. In the following picture we see an embryo magnified 150 times, and we observe the circulation of the blood in the right and left mesenteric artery and the contraction of its walls. Next the vascular area is seen in detail where the blood vessels, as they become farther removed from the embryo, divide into smaller branches, and there is evidence that an increased internal friction results which causes considerable resistance to the flow of the blood. A high pressure is therefore required in the main arteries to drive the blood through the small vessels. Next we see the mesenteric artery demonstrating. the arterial flow of blood; we follow the blood vessel until it divides into several branches, which in turn are often connected by anastomosis; then the arterioles in fore- and mid-brain and the capillaries in the hind-brain; then we see the capillaries of the posterior vitelline area, the posterior cardinal vein, the capillaries of the anterior vitelline vein, all leading back to the mesenteric venous system and reaching the embryo again at the right mesenteric vein, where the even flow of venous blood is nicely demonstrated.

Another film has also been constructed in collaboration with Mr. Fabbri, emphasizing the behavior of transplanted heart muscle. Many experiments have been made in transplanting heart muscles into a tissue culture to determine the conditions which will prolong their life and function. The heart of a chick embryo will beat rhythmically from six to ten days. after having been removed from the animal and transplanted in blood plasma. But if tissues are retransplanted from time to time into a fresh culture, it is known that the muscles will live for more than sixty days.

In order to obtain such cultures for

the motion picture the heart of an embryo is dissected into small pieces about the size of the head of a pin, and each piece transferred to a cover glass and quickly imbedded in a drop of blood plasma. The cover glass is then inverted over a hollow ground slide and sealed with hot paraffin to prevent drying; the prepared slide is then reincubated.

In the picture we see the transplanted heart of an embryo eight days old, which is still beating rhythmically after six days of transplantation ; also a section of heart muscle fifty times magnified showing its rhythmical activity ten days after transplantation.

Scientific authorities agree that one of the most valuable possibilities of such films lies in the fact that they bring within the comprehension of the student mind a wide range of information, thereby encouraging reflection, original thought, and research.

The cinematographic apparatus used for the production of these films is a special and rigid table, and a Debri camera. The source of light should be automatic, as it otherwise would be difficult to keep a subject properly illuminated for a certain length of time. The condenser and cooling trough are attached in front of the are, between the microscope and the light. The vertically arranged camera has attached to it a handle by which it can also be swung in a horizontal position when detached from the microscope. This camera is provided with a direct focus tube through which the image on the film can be watched during exposure. This arrangement is of extraordinary importance, because it is absolutely necessary to watch the living subject while under the camera in order to obtain the best pictures. The mechanism for moving the film is worked by a small electric motor which is connected by pulleys and a leather belt to the shaft of the camera. The micro