Tetrahymena has been shown to ingest and inactivate bacteriophages, such as T4, in co-incubation experiments. In this study, Tetrahymena thermophila failed to inactivate phages PhiX174 and MS2 in co-incubations, although PhiX174 were ingested by T. thermophila, as demonstrated by: (1) recovery at defecation in a pulse-chase experiment, (2) recovery from Tetrahymena by detergent lysis, and (3) transmission electron microscopy. We conclude, therefore, that the phages must be digestion-resistant. Internalized PhiX174 were further shown to be partially protected from lethal damage by ultraviolet (UV) C and UVB irradiation. Finally, ingested PhiX174 were shown to be rapidly transported through buffer in a horizontal swimming, race tube-like assay. The transport and protection of phages may confer evolutionary advantages that explain the acquisition of digestion-resistance by some phages.

Eight parental varieties of barley and the 28 possible F1 and F1 populations were evaluated in spaced plantings in two environments. The traits studied were yield, kernel weight, kernels per head, heads per plant, and height.The average heterosis values of F1's based on midparent means for yield, kernel weight, kernels per head, heads per plant, and height were 21.5, 5.9, 7.1, 7.6, and 3.2%, respectively. When the F1's were compared to the high parent, the average heterosis for yield was 9.1%. The average inbreeding depression for yield in the F2 generation was 26.1%General and specific combining ability variances were obtained from the F1 data, using Griffing's experimental method 4, model II. A substantial amount of additive and nonadditive genetic variance for yield was indicated. Most of the genetic variance for kernel weight, heads per plant, kernels per head, and height was additive.The yield of the best hybrid exceeded the highest yielding parental varieties, Liberty and Traill, by 22 and 38%, respectively. A hybrid advantage of this degree combined with evidence of considerable nonadditive genetic variance for yield indicates the desirability of additional research on hybrid barley. The results reported indicated that performance per se can be used as a basis for initial screening in evaluating potential parental varieties for use in a hybrid breeding program.

Seed of 8 varieties of barley and all possible F1 hybrids from crosses among the varieties were malted to obtain data on 8 malting quality characters. On the average, significant heterosis as measured from the mid‐parents was observed in the F1 hybrids for percent extract, percent malt nitrogen, and percent plump kernels. The F1 hybrid average for percent extract was intermediate between the mid‐parent and high‐parent average. F1 hybrid averages for percent malt nitrogen and percent plump kernels were similar to the low‐parent and high‐parent averages, respectively. The average value for the 28 F1 hybrids and average mid‐parent value did not differ for percent wort nitrogen, ratio of wort to malt nitrogen, diastatic power, 6‐amylase, or β‐amylase. For these characters, with only two exceptions, the individual F1 hybrids did not differ significantly from the average of their parents. Only 7 of the 28 F1 hybrids were judged to be acceptable for all 8 malting quality characters. Six of these had an acceptable malting variety as one parent. Malting quality in the F1 hybrids appeared to depend largely on the frequency of favorable genes with additive effects, although for percent extract, percent plump kernels, and percent malt nitrogen there was evidence for genes having dominance and or epistatic effects.