M.S.

M.S.

On the basis of the present data it would seem that there is no marked relationship between the surface tension and the degree of polymerization of nitrocellulose solutions of normal butyl acetate as determined by the Du Nouy method. It should be noted that no great precision is present in the recorded data. A slight change in surface tension due to a difference in the degree of polymerization could easily be more than offset by errors in measurement. The solutions become much more viscous with increased concentration. This limited the range over which the surface tension could be measured with any degree of accuracy. For with highly viscous solutions the ring would be pulled slowly from the surface making it extremely difficult to determine the exact force required for the break. A second effect was that with increasing concentration a film of the solution adhered across the ring. The data indicates that there is no great change in the surface tension with varying concentration within the range studied. / M.S.

An analytical summary of this study indicates that: 1. The preparation and use of farm maps is standard practice throughout the state in teaching vocational agriculture. 2. The average time devoted to mapping approximates 260 minutes in the eighth grade, 207 minutes in the ninth grade, 149 minutes in the tenth grade and 107 minutes in the eleventh grade, or a total of 723 minutes devoted to mapping in each department in all grades. 3. No standards have been set up by which results in mapping can be compared, however, instructors rate two-thirds of the maps being made as medium in accuracy and one-fourth as high in accuracy. 4. Data used in making the farm maps are obtained from many sources, the most common in order of importance being: deeds, memory of the pupil, collected by the pupil, maps or plats prepared by the Soil Conservation Service or the Agricultural Adjustment Administration. 5. The simplest type of equipment is used in the preparation of the maps, consisting of pencil, scale, pen, protractor, pantograph, ruler, T-Square, and drawing boards; the pencil and scale being most commonly used. 6. Many difficulties are enoountered in the preparation of the maps, one or more being listed by 96 per cent of the departments reporting in the study. 7. Maps are recognized as of practical advantage to the pupils in land-use planning, planning for soil conservation, and for studying jobs in farm management. They may be of use to boys entering the military service. / M.S.

This study gives the activities of two groups of preschool children during the morning session of a nursery school. Purpose: the purpose was 1) to perfect a reliable technique for measuring the behavior of nursery school children; 2) to record and analyze the behavior of the entire group of children enrolled at the Virginia Polytechnic Institute in the winter quarter of 1943; 3) to compare the behavior of five of the nursery school children in 1942 with their behavior in 1943. Subjects: Fourteen children of preschool age enrolled at the Virginia Polytechnic Institute during the winter quarter of 1942 and the winter quarter of 1943, were subjects. The behavior of five of these children was studied during both of these periods. Methods, definitions, and procedure. The observational methods and definitions of behavior used by Neidengard (6) in 1942 were followed in this study. Two observers, who previous to the study had achieved percentage of agreement, recorded for five minutes at a time the behavior of a single child, rotating observations from one child to another until three hours had been secured for each of ten children. This material was studied by the analysis of variance method. The data for the five children in 1942 was taken from Neidengard’s original material. / M.S.

A literature review of rubber-bearing plants in the United States was made, and the essentials of distribution, ecology and rubber content presented in condensed form. Filed lettuce of the specie Lactuca scariola was investigated to determine its place among the other rubber-bearing plants. Nearly pure stands of natural growing wild lettuce were harvested and the weights of plant material determined. Yields up to 2,830 pounds of dry leaves together with 5,760 pounds of dry stems per acre were obtained. The seasonal variation in rubber content and resins of one natural growing wild lettuce stand was studied from the time of the appearance of flower buds to the end of the growth cycle. At this time of maximum rubber content of this stand the calculated yield was between 1.16 and 1.57 pounds of rubber per acre. An experimental planting was undertaken to determine rubber content, resin content, and growth and cultivation characteristics of the earlier stages of growth. Young plants gave up to 0.339 percent rubber and a calculated yield of 13.7 pounds of rubber per acre. Drying temperatures up to the 180°F gave no decreases in rubber content during drying. The rubber content of harvested plants was found to decrease rapidly on exposure to sunlight. At least 10.7 percent of the seeds were found to have the power of germinating soon after ripening. Seeds ripened in the fall were found to have between 49 and 68 percent germinating power. / Master of Science

no abstract provided by author / Master of Science

M.S.

Two groups of cows were fed a ration in which three pounds of a grain mixture was used to every four pounds of hay. Two cows (Test Tube and Deborah) were fed Timothy hay with a grain mixture containing yellow corn. The other three cows (Dolly, Connie and Dot) were fed Alfalfa hay with a grain mixture containing white corn. The grain was also modified for protein balance. Relationships of carotene and Vitamin A concentrations in the blood, milk and feed were then studied. An attempt was made to correlate the various factors involved, the variables being: period of gestation; time after calving; intake of the vitamin and its precursor in the feed; milk produced; percent of the concentration of Vitamin A activity of blood and milk represented by carotene; total Vitamin A activity of the same; and, the efficiency of the secretion in the milk of the Vitamin A activity of the feed ration. The methods of determination of the carotene and Vitamin A (together constituting the Vitamin A activity) are given with details of the calculations. Milk was collected on the first, third and fifth day after calving and at approximately monthly intervals thereafter. Having begun the experiment with the cows in various stages of gestation, it was possible to obtain only six samples from Dot while ten were collected from others. The blood samples also were taken monthly. The feeds were analyzed at three monthly intervals and the rate of loss of Vitamin A activity observed. Minimum values were used in all calculations. / M.S.

A brief investigation was made of various organic and inorganic solvents for the dissolution of urinary calculi in vitro and Albright’s (1) citric acid buffer and a solvent designated in this investigation simply as “G” (33) were shown to be the most efficient solvents. Further investigation showed that something was necessary to increase the efficiency of these solvents, as the dissolution would proceed to a certain point where the solvent ceased to act. It was at this point that the investigation changed its course and the attack was centered on the organic colloidal matrix in the structure of the stone. It is a well known fact that this organic matrix is resistant to weak acids and bases (30) and therefore the course of the investigation pointed to those most remarkable agents, “the enzymes”, which due to their enormous amount of surface energy are capable of producing astonishing results. The enzymes investigated were not selected for their specific action, but they were selected for the purpose of studying the effect of their surface energy on the colloidal matrix of urinary calculi. The investigation indicates that a calculus pretreated with urease for fifteen minutes, followed by a 6 hour irrigation with “G” (33) solution is sufficient to cause dissolution and disintegration in nearly all of the one hundred calculi selected at random. (See Table 5) The ability of urease to hasten disintegration may be due to its activity on the colloidal matrix, causing it to swell, thereby giving back the former hydrotropic properties mentioned by Snapper (52). Colloidal material was isolated from a large calculus and was subjected to the action of urease. After 6 hours the colloids from the calculus had swollen approximately five hundred times their original volume, and changed from a dark brown-colored material to a white translucent gel. These organic colloidal matrices of urinary calculi are apparently of a reversible nature and irreversible as investigators have assumed in the past (30). Investigations were made and reported in various sections of this paper on the ability of other enzymes, peroxide, and acids to act as dissolution agents or as aids to dissolution. An efficient in vitro irrigator Fig. 1 is described and its merit in the irrigation of urinary calculi lies in the facts that its construction is simple, its rate of flow can be accurately regulated by a slight manipulation, and the calculus can be treated in various ways without removing it from the original crucible. It now remains for the urologist to investigate the possibility of in vitro dissolution, using the above auxiliary agent. It is suggested that the urease might be used simultaneously with the irrigation solvent. / Ph. D.