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The effect of nitrogen fertilization on yield and composition and animal selectivity of Midland bermudagrass (Cynodon dactylon) was studied; three forage sampling techniques were used. Fifty-three hectares of bermudagrasss were divided into 12 pastures, and each pasture was fertilized in three split applications (May, July and September) with one of three levels of N (67, 202 and 336 kg N/ha) and one application (May) of P2O5and K2O on the basis of soil analysis. Forage production was determined monthly by cage clipping (CC) under wire exclosures. Esophageal fistulated cows (12) and calves (12) were used to sample the composition of bermudagrass being selected (ES). Hand-clipped (HC) samples were used to estimate yield and quality of available forage. The high level of N fertilizer increased total and monthly average DM yield (P<.05) over that of the low level. Average total yields were 6,716 and 8,494 kg/ha in the low N and high N pastures, respectively. Chemical analysis of CC samples indicated that crude protein (CP) generally increased with increasing levels of N fertilizer in months when adequate moisture was available. However, overall average CP values were 15.6, 15.1 and 15.1% for low N, medium N and high N, respectively. In vitrodry matter disappearance (IVDMD), CP, gross energy (GE), and residual ash decreased from trial 1 (May) to trial 2 (July), whereas acid-detergent fiber (ADF), lignin and cellulose increased from trial 1 to trial 2. Animals selected forage that contained more CP and residual ash, and less GE and cellulose in trial 2 than trial 1. IVDMD and CP values from CC samples were more similar to ES samples than were values from HC samples.

Cells of Escherichia coliwill reduce sodium selenite to elemental selenium. Examination by electron microscopy of E. colicultures grown in the presence of sodium selenite show selenium deposited on the cell membrane and cell wall but not in the cytoplasm.

Factors affecting the determination of histidine decarboxylase activity in adult rat tissues have been studied. The optimal conditions vary from tissue to tissue, and the most potent sources of the enzyme are the pyloric part of the stomach, the liver and the duodenum, with less in the kidney. There is no relationship between the histidine decarboxylase activity of a rat tissue and the amount of histamine it contains.

The rate of motion of a loaded wire through ice has been measured as a function of temperature. The experiments show that a finite motion is still present at temperatures which exclude the possibility of pressure melting. Reasons are advanced which suggest that the explanation of this behaviour may be associated with a surface film between the ice and the wire.

AbstractA study was made of the resistance to cyclodiene insecticides in the root maggots H. cilicruraand H. lituratainfesting tobacco in southwestern Ontario; the resistance tests were made with dieldrin by the WHO impregnated-paper method. Field-collected adults classifiable as H. lituratashowed a dieldrin-resistance which did not extend to DDT; the few F1offspring obtainable by laboratory rearing were highly dieldrin-resistant. A strain of H. cilicruraoriginating from a collection of both species made at Delhi in 1960, and considered at the time to be dieldrin-resistant, proved to be just as susceptible to dieldrin as the Chatham laboratory strain. Individuals of H. cilicruraadmixed with dieldrin-resistant H. lituratain a collection made at St. Thomas in August 1962 were all susceptible. The hypothesis is offered that the reversal in the proportions of the two species on tobacco in recent years is partly due to a difference between them in that H. lituratais capable of cyclodiene-resistance whereas H. cilicrurais not.

AbstractThe inheritance of dieldrin-resistance and DDT-resistance was studied in a laboratory colony of the spotted root maggot Euxesta notatacollected in 1960 at Delhi, Ontario. By appropriate selection methods the colony was divided into 4 strains, namely dieldrin-resistant, dieldrin-susceptible, DDT-resistant and DDT-susceptible. Crosses made between the R and S strains showed that dieldrin-resistance segregated sharply, and was inherited as if due to a single gene allele. An excess of heterozygotes over that expected suggested a certain amount of over-dominance with respect to survival. DDT-resistance did not segregate sharply, but the results of the various crosses were in agreement with the idea that this factor, which was very slightly dominant, was due to a single gene allele. Cross-resistance data for R and S strains indicated that dieldrin-resistance and DDT-resistance were completely separate entities in this species.

1. The influence of adenosine cyclic 3′,5′‐monophosphate (3′,5′‐AMP) and of drugs believed to increase or decrease its concentration in the tissues has been determined on the response of vascular and uterine smooth muscles to catecholamines. Generally, drugs believed to increase tissue content of 3′,5′‐AMP potentiated the responses and those believed to decrease it depressed them.