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A disarmed derivative of the Ti:R772 cointegrate plasmid pAL969 was used to produce transgenic plants of a commercially important inbred line of oil–producing sunflower. A chimeric gene (neo) composed of the coding sequence of neomycin phosphotransferase (NPT) and 5′ and 3′ sequences from octopine synthase permitted the selection of kanamycin–resistant (Kanr) callus capable of plant regeneration. Kanamycin inhibited plant regeneration, precluding simultaneous plant regeneration and selection for resistance to the antibiotic. Progeny analysis of transformed seedlings indicated Mendelian inheritance of neo. Expression of neo in transformed seedlings and plants indicated that the use of a Ti–derived promoter does not guarantee constitutive expression of the foreign gene. These results demonstrate that the introduction of foreign genes via Agrobacterium–mediated transformation can now be used for agronomic improvement of sunflower.

The use and limitations of linear-elasticity equations for describing mechanical properties of compacts is discussed; the limitations occur because compacts are porous, viscoelastic, nonhomogeneous, Mohr bodies. Awareness of these properties permits meaningful comparisons to be made. Ignoring limitations may result in unjustified conclusions. Special care during measuring mechanical properties of compacts is required. The mechanical criteria for a successful formulation are good flowability for powders and adequate strength without fracture for compacts. Interparticle attraction is spontaneous but particle contact numbers and size are limited by mechanical preclusion. Plastic deformation and fracture mechanics are controlling mechanisms with the magnitude of elastic constants having little effect on the successful processing. General compaction characteristics can be appraised by using combinations of properties, e.g., specific tableting indices.

Closed sterile catheter drainage has markedly reduced the incidence of nosocomial urinary tract infections. Infections that occur during closed drainage must ascend by colonizing the catheter or urethra. Our study compared adherence by different bacterial species to different catheter surfaces. We found no bacteria adhering to the hydrophilic catheter surface. Of the gram-negative bacteria Proteus mirabilis showed the greatest adherence to the other catheters and it, like most bacteria, showed the most marked adherence to the red rubber catheter.

A die with a flexible wall was constructed and evaluated on a specially modified instrumented rotary tablet press. The design permits an inward deflection of the die wall by a side punch, which rolls past a side compression roll during compression-decompression. The side compression roll is instrumented to monitor the applied side compression roll forces. On decompression, return of the die wall to its original position permits release of residual die wall pressure. The decreased residual die wall pressure can decrease fracture and capping of tablets for problem formulations. The performance was tested on three experimental formulations. For these formulations, tablets made in a conventional die exhibited severe capping problems. However, most tablets compressed in the special die were superior. With proper adjustment of punch and die wall compression forces, excellent tablets could be manufactured. The merits of the special die and modified tablet machine are substantiated, although this initial design did not provide adequate die wall pressure for all formulations. Further engineering efforts could result in practical production equipment.

Leukocyte exchange between the hemopoietic tissues of parabiotic rats was studied subsequent to giving multiple injections of 3H-thymidine to one member of each pair while arresting the cross-circulation. Cell types that migrated from one parabiont to the other were segmented granulocytes, small, medium and large lymphocytes, immunoblasts, monocytoid cells, macrophages or their immediate precursors, and plasma cells. Evidence for the transformation of circulating cells to other cell types was rarely seen. The long-lived small lymphocytes were equilibrated between parabionts, suggesting that this is a single pool of cells with respect to kinetic behavior and recirculation. There was no evidence for a trephocytic function of lymphocytes. A small number of bone marrow lymphocytes coursed directly to lymph nodes and spleen. Evidence is given for a limited recirculation of short-lived lymphocytes of thoracic duct lymph (TDL), as well as for long-lived cells. Only a few immunoblasts of TDL recirculated. The majority of cells that entered the white pulp of the spleen were long-lived small lymphocytes, while the majority of immigrant cells to the red pulp were monocytoid cells and granulocytes. Many small lymphocytes originated in splenic red pulp and entered the blood. No immigrant cells to the thymic cortex were noted, although some small lymphocytes and monocytoid cells entered the medullary areas. Immigrant cells to the bone marrow (less than 2% of the cells in marrow) included monocytoid cells, small lymphocytes, and plasma cells. Evidence for the direct transformation of a circulating cell into a committed blast, based on reduction in grain count, was noted only in bone marrow.

These radioautographic studies using parabiotic rats and partial marrow shielding showed that cells responsible for recovery of irradiated bone marrow had their origin in the shielded marrow. Three morphologically distinct cell types appeared in the blood of these parabionts, mature granulocytes, small lymphocytes and monocytoid cells. The monocytoid was the major cell type which crossed from the shielded to nonshielded marrow, and the observations suggested that it is this cell which served as a stem cell for both the erythrocytic and granulocytic cell lines. Labeled erythroblasts and myeloblasts were observed in the recovering marrow, and the labeling intensity of these cells indicated that they were the second or third division products of labeled immigrant cells. The effect of marrow shielding upon the recovery of lymphopoiesis in spleen, thymus, lymph nodes and bone marrow is also discussed.

Single and multiple injections of tritiated thymidine were combined with radioautography to study the rates of proliferation and interrelationships of the various cell lines in the mesenteric lymph node of the rat. The appearance and labeling patterns of the different cells are described from studies of both smears and tissue sections. Reticular cells exhibit wide variations in labeling intensity, phagocytize labeled lymphocytes, and become labeled in high percentages only when TTH is administered over a period of many days. Other slowly proliferating cell types include small lymphocytes, fat cells, endothelial cells and mast cells. Rapidly proliferating cell lines include plasmablasts, hemohistioblasts, proplasmacytes and large lymphocytes. The generation time of plasmablasts and hemohistioblasts was determined to be approximately 9 and 12 hours respectively. Mature plasma cells constitute a non-dividing population which is renewed in lymph node in not more than 5 days. Evidence is presented that the most primitive cells in the lymphocyte and plasma cell lines are the hemohistioblasts and plasmablasts respectively. Reticular cells most probably are not stem cells. No evidence is found to support previous reports that plasma cells derive from lymphocytes.

Radioautography with tritiated thymidine has been utilized to examine the turnover rate and origin of small lymphocytes in the bone marrow of the guinea-pig. Very few marrow lymphocytes were initially labeled by a single injection of tritiated thymidine, but thereafter the number of labeled lymphocytes rapidly increased to high maximum levels at 3 days. Analysis of the labeling curves and grain counts indicates that the population of marrow lymphocytes is maintained in a dynamic steady state with an average turnover time of 3 days or less. Suspensions of bone marrow cells were isolated from the circulation within intraperitoneal diffusion chambers after short-term labeling with tritiated thymidine in vivo. Although very few small lymphocytes were labeled when introduced into the diffusion chambers, a considerable percentage became labeled during the subsequent culture period. Tritiated thymidine was also administered intravenously whilst excluded from one hind limb by the application of an occlusive compression bandage for 20 minutes. Very few labeled small lymphocytes were found after 72 hours in the tibial marrow of the initially occluded limb, whereas the normal high percentage was labeled in the control tibial marrow. These experiments do not demonstrate any large-scale influx of small lymphocytes from the blood stream into the marrow parenchyma. They suggest that newly formed small lymphocytes appear in the marrow as a result of the division of locally situated precursor cells, but the mechanism of intramedullary lymphocytopoiesis is uncertain. "Transitional" cells, intermediate in morphology between blast cells and small lymphocytes, synthesize DNA and are actively proliferative, but they do not appear to account fully for the rate of lymphocyte production. Certain large, undifferentiated labeled cells appeared in the bone marrow as a result of hematogenous migration. Some implications of these findings are discussed.

Tritium-labeled thymidine was given by either intraperitoneal or intravenous injection to 13 male guinea pigs of approximately 400 Gm. weight. At times varying from 1 hour to 30 days after the administration of thymidine, thoracic duct lymph was obtained and examined for the presence of labeled cells. After a single dose of thymidine, a steady stream of labeled lymphocytes, ranging from 2 to 7 per cent of the total cells, enters the blood over the period studied. The intensity of the labeling appears to diminish gradually. Labeled large and medium lymphocytes were found in the lymph during the first hour. Labeled small lymphocytes began to appear in the fourth hour, in small numbers, and thereafter increased, whereas the proportion of labeled large and medium lymphocytes steadily diminished. This sequential appearance of large, medium and small lymphocytes is interpreted as indicating the pattern of development of the cell series. The labeled small lymphocytes appearing in the lymph are considered to be newly formed from precursor cells located in the various lymphatic tissues.

An apparatus and procedure for measuring the static friction coefficient of powders in simple beds are described. The relative merits of three variations of the shear cell are considered. A sandwich of powder between two surfaces covered with sandpaper is satisfactory under most experimental conditions. Examples of the effect of relative humidity, time under load, mechanical vibration of the powder bed, and variations in the experimental procedure are presented. Reproducible values of the friction coefficient can be obtained readily if the experimental and environmental conditions are standardized. The results of the experiments suggest that a single value of the friction coefficient applies only to a specific powder bed. In practical applications the entire range of values that may be encountered must be within acceptable limits.

When Lewis rats were exposed to antilymphocytic serum, produced in rabbits, to Lewis lymphoid cells, the transformation of their thoracic duct lymphocytes in response to foreign lymphoid cells was markedly reduced in comparison with that in response to similar cells from donors treated with saline or normal rabbit serum. It is suggested that the mixed lymphocyte reaction may be used as an in vitro test for the in vivo activity of antilymphocytic serum.

The probable mechanism of the control of floc structure by polymeric materials is developed from theory of polymer stabilization of disperse systems. Techniques that provide some insight into the nature of the floc are described. In predicting shelflife, these concepts shift the emphasis away from the evaluation of sedimentation and caking to a study of potential structural changes of the floc.

(i) Morphological studies relating to the origin and differentiation of the definitive germ cells in vertebrates have, as indicated, resulted in conflicting views. In many instances two or more competent investigators who have studied the same form have reached different conclusions. (2) Some contend that the germ cells are set aside from the soma during the early stages of embryonic development, and that these alone serve as the progenitors of the functional sex cells. (3) Others recognize an early differentiation of sex cells but hold that these are supplemented by others produced from the somatic epithelium of the gonad in late embryonic or post‐embryonic stages. (4) Another group recognizes the early differentiated cells as germ cells but contend that these all degenerate and that the definitive ones are formed from the germinal epithelium. These degenerating germ cells are believed by certain authors to be a phylogenetic recapitulation of the condition in lower forms. (5) Finally, yet another group contends that the so‐called primordial germ cells are not germ cells at all but are enlarged cells in some stage of mitosis or in some specific metabolic phase. This group believes that all germ cells are derived from the somatic cells of the germinal epithelium. (6) Experimental work supports the view that the primordial germ cells, which are recognized early, are the progenitors of the definitive sex cells. When these primordial germ cells are prevented from reaching the site of the developing gonad the individual fails to develop sex cells, although a sterile gonad and its associated structures may develop. (7) I suggest that the observed proliferation of germ cells from the germinal epithelium, reported by numerous investigators, can be interpreted in another way by a thorough study of the enlarged germ cells in relation to the epithelium. It seems probable that the cells of the epithelium, which form functional sex elements, are not and never were a part of the mesothelial covering, but are cells which were segregated early, and are merely stored in the epithelium.

The conservation of retention-form dentin in this method could increase patient comfort, reduce treatment time, and lessen fatigue for dentists.

A model for tablet bond formation is developed. It assumes that attraction forces arise from dispersion forces between surfaces with spherical curvature. The radius of these surfaces depends on the amount of plastic deformation produced during compression. The radius of curvature is calculated by using Hertz's equation for elastic deformation, which is assumed to hold during decompression. The number of contact points per unit cross section is taken as a simple multiple of a number deduced from the particle size, the indentation hardness values, and the solid fraction. A similar approach is used to replace the area per contact point produced when under compression. The resulting equation is used to estimate the bonding index. Values corresponding to the lower range of experimentally determined bonding indices are obtained. Arguments are presented to suggest that large values of the bonding index (tensile strength/indentation hardness) probably result principally from plastic (including viscoelastic) deformation during decompression. Nondispersion forces may contribute but are not believed to be of sufficient magnitude to account for the total bond for materials that exhibit a large value of the bonding index.

Symptoms of regional enteritis are variable, its onset is most often insidious, and the history of lower abdominal pain, diarrhea, fever, loss of weight, anemia, abscesses, and fistulas usually extends over months or years. The sequence of routine diagnostic procedures should include scout roentgenograms, febrile blood agglutination studies, warm stool examinations, proctosigmoidoscopic and roentgenologic examinations of the colon. In the absence of obstruction, it is important to give barium by mouth for interval roentgenologic studies of the small intestine. The typical finding in terminal ileitis, the "string sign," is often seen when barium given by enema regurgitates through the ileocolic junction into a stenotic segment of ileum and reveals a dilated segment proximal to the lesion. Sinuses and fistulas may also be revealed. Each patient presents an individual problem. Recurrences after operation are well known, but the mortality is low. Remission with complete healing sometimes occurs, and pessimism as to surgical treatment is unwarranted.

Lake Superior was chosen as an experimental site to compare sound absorption of freshwater with the results of absorption measurements in seawater. The relaxation-like absorption at 1 kilohertz occurring in seawater is also present in freshwater. A relaxation related to the structural characteristics rather than to the salt content of water may be responsible for the anomalous absorption.

INGESTED nuclear material has long been known within the reticular cells of normal lymphoid tissues and has led to the suggestion that the reticular cell may re-utilize lymphocytes and incorporate their deoxyribonucleic acid (DNA) into newly formed cells1,2. During autoradiographic studies of lymphocytes in the bone marrow, observations have been made on reticular cells including the ingestion of nuclear material labelled by the prior incorporation of tritium-labelled thymidine during DNA synthesis. Male Hartley guinea pigs weighing approximately 400 g were given a single, intraperitoneal dose of tritiated thymidine (1 µc./g body-weight: specific activity, 1.9 c./mM). After intervals of 25, 48 and 72 h humeral bone marrow was gently suspended in homologous serum and examined in smears. Auto-radiographs of smears were prepared by coating with melted Eastman Kodak NTB3emulsion, exposing for 14 days and staining through the fixed emulsion with MacNeal's tetrachrome stain.

Omission of 2,4-dichlorophenoxyacetic acid (2,4-D) from batch cultures of sycamore (AcerpseudoplatanusL.) caused growth cessation after an initial period of exponential growth. The presence of white light reduced the amount of growth after 2,4-D withdrawal. Growth cessation, in the absence of 2,4-D, was accompanied by the accumulation of the free amino acid, serine. This accumulation began before the cessation of growth and was rapidly reversed by the re-addition of 2,4-D.