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Portrays the role of developmental genetics in dealing with ways phenotypes come into being through the action of genes. Presents a complete discussion of the Creeper domestic fowl--its genetic basis, morphology, embryological history, and the experimental work that led to an understanding of how this gene affects early development to produce the morphological features seen as the outcome of the developmental process. Lecture given by Dr. L. C. Dunn.
Shows the parts of a single ram vertical machine; how to interpret the blueprint of a broaching tool; how to install broaching inserts for straddle broaching; how to mount the toolholder with its assembled broaching tool; how to mount and adjust the work fixture; and how to surface-broach at production rate.
Shows how surface plates are used to check the flatness of surfaces, types of scrapers, how to remove high spots, and how to determine when a surface is scraped flat.
Demonstrates independent segregation by different pairs of genes using Mendel's data. Emphasizes the chromosomal activities during meiosis which are responsible for independent segregation. Describes the Punnett Square and the branching track methods of combining gametes at random. Discusses test crosses and linkage (as the exception to independent segregation), and shows that independent segregation proves the separability of the germ plasm into many gene pairs. Depicts the role of genetic recombination in speeding the process of evolution. Lecture by Dr. E. Altenburg.
Pictures reproductive isolation originating through interspecific hybridization, via amphyploidy (radish-cabbage, new world cottons, goatsbeard species), and by means of introgression (tobacco, rose family, maize-teosinte), and by the direct recombination of the products of crossing and the establishment of recombinations (larkspur). Specifies ways in which natural selection can aid reproductive isolation directly or indirectly. Depicts hybridization as a powerful stimulus in species formation and as a valuable experimental tool for the study of the genetic basis for species differences. Lecture given by Dr. G. L. Stebbins.
Discusses the effect of various levels of inbreeding (self-fertilization, sib matings, half-sib matings, cousin marriages) upon making heterozygous genes homozygous with the consequent loss of vigor. Presents data for the increased risk of genetic defect from cousin marriage in studies of phenylketonuria, of a Japanese population and a French population. The concept and estimation of lethal equivalents are given. Shows how increases in heterozygosity increase vigor (heterosis); hybrid vigor in corn in described in detail. Lecture given by Dr. J. F. Crow.
Portrays the frequency of mutants in the population gene pool as dependent upon their rate of origination and selection coefficient. Discusses the population fate of dominant lethals (retinoblastoma), dominant detrimentals (achondroplasia), and recessive lethals (juvenile amaurotic idiocy). Describes in detail the loads of mutations carried in natural populations of Drosophila pseudo obscura and in man. Points out the fact that while most mutants are detrimental in the normal environment of the species, some may be advantageous in a different environment. Lecture given by Dr. Th. Dobzhansky.
Explains the nature and importance of population genetics. Derives the Hardy-Weinberg equilibrium principle for Mendelian (cross-breeding) populations. Points out that though the Hardy-Weinberg law produces a static gene pool when it applies, mutation, selection, random genetic drift, and migration upset this equilibrium and cause gene frequencies to shift-these factors being, therefore, the principal causes of evolution.
Demonstrates through slow motion and natural photography the positions and movements of the "Hoosier Promenade." Opens with a group of eight dancers performing the introduction to the dance. Shows each pair of dancers, identified by a number, demonstrating the different parts of the dance and how each step flows smoothly into the next. Concludes with the performance of the dance to a record.
Uses animation, slow motion, and real photography to demonstrate the positions and movements of dancers and dancing couples in the "grapevine twist." Shows each part of the dance separately and then shows how each step flows smoothly into the next as the dancers perform to synchronous music.
