permit of a general treatment of blending inheritance. If one attempts to apply to each case a scheme of specially weighted factors, as Punnett has done for size inheritance in fowls and rabbits, he proves nothing except the fact that a factorial explanation of his results is possible, for by properly weighting factors and assuming that some inhibit the action of others, one can fit to his observations a scheme involving either few or many factors. If one factor really has an influence greatly superior to that of other factors in a case of blending inheritance, this will be seen in the production of asymmetrical or multimodal variation polygons in F, and F. If, when adequate numbers are produced, the variation curves of F, and F2 are both smooth, it is certain that no genetic factor of predominant influence is involved in the case, but that several or many factors substantially equal in influence are concerned. Whether many or few can perhaps be ascertained by the method suggested in this paper. I have recently applied it in the study of weight inheritance in crosses between races of rabbits differing in size, with the following results. Three races of rabbits were crossed in all possible ways. The average size of the smallest race, Polish, was 1,404 grams; of the second race, Himalayan, it was 1,875 grams; of the third race, Flemish, it was 3,600 grams. The number of factors indicated as differentiating the races in weight is in the order of magnitude of the differences between the races. See Table III. But the number of factors indicated as differentiating the smallest race from the largest (Polish from Flemish) is apparently too great, since it exceeds the sum of the differences in number of factors indicated as existing in the other two crosses. It is perhaps not to be expected that results more than approximately correct would be given by this method, unless fairly large numbers of both F, and F, individuals have been studied. In the rabbit crosses, the numbers of F, individuals studied were 16, 25, and 27, respectively. The F2 numbers were 50, 62, and 112. The results obtained are sufficient to indicate the probability that in the Polish 2 THE UTAH ACADEMY OF SCIENCES THE fourteenth annual convention of the Utah Academy of Sciences met in the physics lecture room of the University of Utah, Salt Lake City, on Friday evening, April 1, 1921, and continued for three sessions, closing Saturday afternoon with a business session at which the following officers were elected for the ensuing year. President, Dr. Frank L. West, Utah Agricultural College, Logan, Utah. First Vice-president, Professor Hyrum Schneider, University of Utah, Salt Lake City. Second Vice-president, Professor Carl F. Eyring, Brigham Young University, Provo. Secretary, A. O. Garrett, East High School, Salt Lake City. Corresponding Secretary, C. Arthur Smith, East High School, Salt Lake City. Councillors, Professor Harold R. Hage, University of Utah; Dr. M. C. Merrill, Utah Agricultural College, Logan; R. A. Hart, U. S. Reclamation Service, Salt Lake City. Twenty-seven new members were added to the academy's roll of membership, making the largest increase in any one year in the history of the academy. The academy voted unanimously to support the following resolutions: WHEREAS: There is a greatly increased appreciation and use of the recreation and scenic resources of Utah to which an abundant supply of wild life is of great importance in furnishing an opportunity for nature study, fishing and hunting; WHEREAS: The maintenance of proper forest conditions is necessary for the preservation and production of fish and game; WHEREAS: Proper measures to insure a continued supply of fish and game must be based on a scientific knowledge of biological factors involved ; Therefore, be it resolved, That the Utah Academy of Sciences: 1. Emphasize the close relationship between our forests and fish and game conservation. 2. Endorse the recognition by the Forest Service that the fish, game and wild life on the National Forests are valuable resources to be preserved and maintained. 3. Cooperate with the sportsmen, the State Game Department, and Federal departments in order that proper measures to perpetuate the fish and game be undertaken and that the general public, especially the youths, be informed regarding our wild life and the necessity for its protection. WHEREAS: The rapid increase in population of the United States and Canada with its consequent use of agricultural and forest land is threatening the extinction of many native species of plants and animals, and WHEREAS: The preservation of such native species is greatly to be desired, be it Resolved: That the Utah Academy of Sciences endorse the work of the Ecological Society of America in the movement for the preservation of natural conditions in the United States and Canada. Resolved: That it is particularly important that areas with typical plant and animal communities in different states of the union and the provinces of Canada be preserved and allowed to go on with their natural successional changes for the benefit not only of students who are interested in these subjects at the present time, but also and more particularly for future generations. Resolved: That this Academy hereby requests the National Research Council to take cognizance of this important subject and requests said National Research Council to aid in whatever manner may be possible the work of the Ecological Society of America in securing vegetation and animal preserves and sanctuaries for the furtherance of scientific study. Resolved: That a copy of these resolutions be forwarded by the corresponding secretary to Dr. C. E. McClung, chairman of the Division of Biology and Agriculture of the National Research Council. WHEREAS: It is recognized that the timber supply of the nation is rapidly becoming depleted; WHEREAS: The forest resources are of the greatest importance in the economic and industrial development of Utah and of the entire nation; WHEREAS: The maintenance of proper forest conditions on important watersheds is conducive to a regular and continued stream flow and an adequate supply of pure water so essential for domestic, hydro-electric and irrigation use; Be it resolved: That the Utah Academy of Sciences strongly endorses the conservation of forests to the extent of maintaining all potential forest land in a highly productive condition. With this purpose in view, we therefore, strongly urge the adoption of a national forest policy for the entire nation similar to that proposed in H. R. 15,327, introduced in the 3d Session of the 66th Congress, commonly known as the "Snell Bill."' Therefore, be it further resolved: That the Corresponding Secretary be instructed to transmit copies of this resolution to the members of Congress from Utah. The following papers were read at the three sessions of the convention. FRIDAY EVENING, APRIL 1 Symposium of Forests Conservation in Utah Making the forest of Utah a permanent resource, Fungus forest tree diseases of Utah, A. O. GAR- Forests in relation to climate and water supply of SATURDAY A.M. Analytical distillation of shale oil, M. J. GAVIN, Destructive distillation of oil shale, L. C. KAR- Chemistry of the volatilization process, THOMAS VARLEY and C. M. BOUTON, U. S. Bureau of Mines. Metallurgy of the volatilization process, C. C. STEVENS, University of Utah. Function of steam in retorting oil shales, M. J. GAVIN, U. S. Bureau of Mines, and J. J. JAKOWSKY, University of Utah. Reduction of copper from chloride fumes, R. H. BRADFORD, University of Utah. SATURDAY P.M. Decomposition of green manure at different stages of growth, THOMAS L. MARTIN, Millard Academy. The normal temperature as a function of the time, elevation above sea level and the latitude, FRANK L. WEST, Utah Agricultural College. Vitamines in relation to nutrition, W. E. CARROLL, Utah Agricultural College, Logan. Relation of precipitation to height growth of forest tree saplings, CLARENCE F. KORSTIAN, U. S. Forest Service. A twelve o'clock luncheon was given to the members of the academy and their friends at the university dining hall under the efficient direction of Miss Lucy Van Cott, dean of women, University of Utah. Dr. Frank L. Harris, of the Agricultural College, spoke at the luncheon on the general topic of scientific research, emphasizing the importance of stimulating an appreciation of its results in the public mind. C. ARTHUR SMITH, Corresponding Secretary The Sectional Committee is constituted as follows: A. E. Jenks, chairman, Minneapolis, Minn.; E. A. Hooton (Jan., 1921-Dec., 1924), Cambridge, Mass.; Aleš Hrdlička (Jan., 1920-Dec., 1923), Washington, D. C.; Berthold Laufer (Jan., 1921Dec., 1924), Chicago, Ill.; R. J. Terry (Jan., 1920Dec., 1921), St. Louis, Mo.; F. C. Cole (Jan., 1921-Dec., 1922), Chicago, Ill.; Clark Wissler (1921), from the American Anthropological Association, Washington, D. C.; J. Walter Fewkes (1921), from the American Anthropological Association, Washington, D. C. The following papers were read and discussed: The practical value of anthropology to our nation: A. E. JENKS, University of Minnesota. The grouping of Piman languages upon a phonetic basis: J. A. MASON, Field Museum of Natural History. A project for the study of race mixture in the United States: E. A. HOOTON, Harvard University. The peopling of Asia: A. HRDLIČKA, U. S. National Museum. The influence of sex and stock upon the pubic bones: T. WINGATE TODD, Western Reserve University. Variations in the weight of new-born children with particular reference to racial differences; comparative growth of premature and normal children: E. E. SCAMMON, University of Minnesota. A bird's-eye view of American languages north of Mexico: E. SAPIR, Geological Survey, Canada. The scaphoid type of scapula: W. W. GRAVES, St. Louis, Mo. The present state of anthropological research in the Philippines: F. C. COLE, Field Museum of Natural History. The relative dating of Aztec and Pueblo Bonito ruins, by growth rings on the timbers: A. E. DOUGLASS, University of Arizona. Aztalan: S. A. BARRETT, Milwaukee Public Mu seum. Anthropology at the Pan-Pacific Congress: CLARK The American plant migration: BERTHOLD LAU- The Ridatsa Indian: Care and training of the dog and horse: GILBERT L. WILSON, Macalester College. The preservation of Indian remains in Wisconsin: CHAS. E. BROWN, Sec., Wisconsin Archeological Society. The following papers were read by title: Geographical influences upon human culture with special reference to the Great Plains: MELVIN R. GILMORE, State Historical Society of North Dakota. The technique of paleopathology as applied to human remains: Roy L. MOODIE, University of Illinois, College of Medicine. Aboriginal population in California: A. L. KROEBER, University of California. Some vital aspects of the American Indian: FREDERICK L. HOFFMAN, Prudential Life Insurance Company. Waning stone age industries among the Wisconsin Indians: ALANSON SKINNER, Milwaukee Public Museum. Current illogical extravagant estimates concerning the antiquity of man: G. FREDERIC WRIGHT, Oberlin College. The afternoon session of December 29 was devoted to a conference on State Archeological Surveys. On the afternoon of December 30, the section visited the Field Museum of Natural History to inspect the anthropological exhibits and afterwards visited the Newberry Library for an examination of the Ayer collection of Americana. E. A. HOOTON, Secretary, Section H SCIENCE FRIDAY, AUGUST 5, 1921 PARASITISM AS A FACTOR IN DISEASE 1 THE study of etiology or causation is a study of the entire field of medicine from a certain point of view. Every phenomenon assumes an etiological aspect whenever we study it not as an effect to be simply contemplated and described, but as a cause or necessary condition of something that is going to happen. Provided with the information that for certain events to take place certain necessary conditions must precede, we can take steps by controlling the necessary conditions to allow the event to occur or not. Modern medicine has made the concept of causation its own. On it is founded all rational progress in prophylaxis and therapy. First to comprehend the cause, then to intercept and suppress it and thereby to prevent the next step is the kernel of medical science and practise. We project ourselves into the immediate future. The present is only the boundary between what has occurred and what is to happen. To control events we must know how to distinguish those conditions which are necessary from those which are merely associated and coincident. The history of medical science, notably during the past half century, has clearly shown that observation of disease as it occurs in everyday life must be associated with the experiment. By observation I mean a survey or study of the phenomenon as a whole; by experiment, the observation of isolated parts of the entire phenomenon, the other parts being meanwhile eliminated or controlled by special devices. Observation and experiment, alternating, cooperating, and reacting on each other, are the only sure guides to a rational interpretation of disease. Nature is continu 1 Paper read at the annual meeting of the Association of American Physicians, May 10, 1921, as part of a symposium on etiology or causation of infectious diseases, ally experimenting and observation is simply taking notes in this great life experiment. Without it the laboratory experiment would lack reality, for it is simply a page torn out of the book of nature with the unknown factors controlled or eliminated. To get at the facts of disease it has been found necessary to bring experiments as close as possible to the natural phenomena without losing control of the details. The necessary association of observation and experiment in interpreting the conditions determining disease may be illustrated by the familiar one of the noise and the flash of gunfire. At a distance we see the flash and then hear the explosion. We might infer that the flash was a cause of the explosion, since it always precedes it. As we approach the scene of operations the noise follows the flash more and more quickly and close by the two reach our senses almost simultaneously. We then are in doubt whether the flash is a cause or merely an accompanying phenomenon. Our static observation at a distance fails to inform us correctly. The experiment of approaching the firing compels us to revise our original notion of causation and to make a further study of the entire phenomenon. The gist of the etiological problem is thus to determine what are necessary conditions and what merely secondary phenomena. The experimental method has been of immense service in laying bare the dynamic or causal relation, in other words, the true sequence of events. On the other hand, experiment too far removed from the actualities has frequently led astray when its results were too literally accepted and not controlled by observation of the entire phenom enon. In the environment of man and within the human mechanism itself there are many conditions operative towards disease. This entire group or sequence of conditions, rather than any single factor in the group or sequence, may be regarded as the cause. If any one of these conditions is neutralized or controlled, the disease may not occur or if in progress it may take another course. Naturally these conditions have different values. They may be judged from their accessibility to control, i.e., from a practical standpoint, or from the point of view of the physicist weighing them according to their energy values. We have hardly reached the stage, however, when the conditions favoring disease can be accurately measured. We must still deal with them as entities. Their qualities must engross our attention and their quantitative relations remain for a future, more exact medical science to weigh and measure. The forces and conditions controlling disease are a mixture of heredity, environment, and parasitism. How can these factors be taken from their natural relations and studied individually without upsetting the delicate balances of causation? Where can we begin to test experimentally the observations we make about natural occurrences? Obviously some very careful surgical operation is necessary in carving out our field of work. In so doing we must realize that we become piece workers tinkering with only a part of nature's mechanism. Our finished product must be skillfully fitted into the larger mechanism. In attempting to limit our discussion to parasitism as an etiological factor in disease, I realize the difficulties mentioned. We have not only the different categories of environment, heredity and parasitism acting on one another, but within each category we have the animal body reacting with the factors like a chemical process swinging back and forth towards a state of equilibrium. Finally, we have in parasitism two living variable organisms capable of adjusting themselves towards each other in a remarkable degree. When, about forty years ago, methods were devised by Robert Koch to make a beginning in the accurate study of bacteria as living agents of disease the contemporary scientific world realized that here were, to all appearances, agencies that could be separated from their environment, their life history and activities subjected to rigid investigation, and their relation to disease opened to demonstration. It is not surprising, therefore, that the bacteriologists of somewhat more than a generation ago, started on their way by these |