Vegetable Plant Part Relationships. I. Effects of Time and Population Density on the Shoot and Storage Root Weights of Carrot (Daucus carota L.)

Chantenay carrot plants were grown in replicated plots containingdensities of 25, 64, 130 and 245 plants m^–2 and harvestedon 20 weekly occasions giving a total of 360 pairs of d. wtsand 13908 pairs of f. wts of shoots (s) and roots (r). The relationshipbetween the logarithms of s and r was curved for plants sampledon successive occasions from the same density but it was linearfor plants sampled on a single occasion, both within and betweendensities. A good overall relationship was In s = a+0.805 In r, where the intercept (a) ranged in approximately equal stepsfrom +1.2 to –1.1 at the first and last harvests respectively.Except for some systematic deviation from this equation at earlyharvests, the above relationship fitted the data well irrespectiveof the wide range of density and whole plant weight. Daucus carota L. carrot, root/shoot weight, population density, growth analysis     

Vegetable Plant Part Relationships. II. A Quantitative Hypothesis for Shoot/Storage Root Development

A simple quantitative formulation of the concept of the controlof partitioning of assimilated carbon by the behaviour of plantcomponents as competing sinks is developed. An equation, In s = + In r—t, relating shoot (s) and storage root (r) d. wts, and the lengthof growth period (t), is constructed by considering possiblefates of imported assimilates into different plant parts. Thevalues of the equations' parameters depend on the relative sinkactivities of the plant parts, tissue respiration rates andinitial weights of plant components. The equation closely fitteddata collected from a number of carrot and beet experimentsin which planting density had been varied. Estimates of shootand storage root maintenance respiration rates, derived fromthe parameter , were of the correct order of magnitude. Othersets of experimental data are also discussed in the light ofpredictions of the theory and possible uses and extensions ofthis approach to assimilate partitioning are briefly discussed. Daucus carota L., Beta vulgaris, carrot, red beet, partition of assimilated carbon, maintenance respiration, storage root     

Phylogeography of lions (Panthera leo ssp.) reveals three distinct taxa and a late Pleistocene reduction in genetic diversity

Lions were the most widespread carnivores in the late Pleistocene, ranging from southern Africa to the southern USA, but little is known about the evolutionary relationships among these Pleistocene populations or the dynamics that led to their extinction. Using ancient DNA techniques, we obtained mitochondrial sequences from 52 individuals sampled across the present and former range of lions. Phylogenetic analysis revealed three distinct clusters: (i) modern lions, Panthera leo ; (ii) extinct Pleistocene cave lions, which formed a homogeneous population extending from Europe across Beringia (Siberia, Alaska and western Canada); and (iii) extinct American lions, which formed a separate population south of the Pleistocene ice sheets. The American lion appears to have become genetically isolated around 340 000 years ago, despite the apparent lack of significant barriers to gene flow with Beringian populations through much of the late Pleistocene. We found potential evidence of a severe population bottleneck in the cave lion during the previous interstadial, sometime after 48 000 years, adding to evidence from bison, mammoths, horses and brown bears that megafaunal populations underwent major genetic alterations throughout the last interstadial, potentially presaging the processes involved in the subsequent end-Pleistocene mass extinctions.     

THE DISTRIBUTION OF GROUP D STREPTOCOCCI IN CATTLE AND SHEEP

Numbers and types of Lancefield group D streptococci have been determined in samples from the colons of 17 cattle and 9 sheep. Mean total streptococcal counts of 8 × 10⁴/g in cattle and 2 × 10⁶/g in sheep were obtained. Streptococcus bovis was found in every sample and was the predominant species in 15 of the cattle and 6 of the sheep. Other group D streptococci ( Strep. faecalis, Strep. faecium and Strep. durans ) were rare in cattle, but in sheep they formed a significant proportion of the population. Of 60 Strep. faecium, Strep. durans and related strains, 51 fermented raffinose. Many of the strains of Strep. faecium were also atypical in that they fermented sorbitol and appreciably reduced tetrazolium in broth at pH 6.0.
Strep. bovis remained the predominant streptococcus in faeces samples from 4 dairy cows when they were tested again after an interval of 17 and 18 months.     

Postmaturity syndrome; the obstetrician's role in management

The obstetric problem of going past the date of expected confinement has no medical significance, provided the fetus in its demands does not outgrow placental capability. The problem of relative placental insufficiency, however, is a serious one with a total fetal wastage in the neighborhood of 15 per cent. Antepartum indications of such placental insufficiency have not yet been well documented. However, a decrease in the fundal measurements and particularly where associated with an otherwise unexplained loss of maternal weight has proved an ominous sign. In a study of application of reported criteria for determining when a patient is "at term" by vaginal cytologic methods, the results were approximately 75 per cent accurate. Cytologic studies when coupled with other physical findings may be of assistance in determining in which cases labor should be induced and in which the fetuses should be accorded the special attention that is demanded by the chronic state of low grade anoxia.     

Radiation of pelvic malignant disease

At present, progress in the treatment of cancer consists of more extensive excision or more thorough irradiation. The cure rate of pelvic cancer is proportionate not so much with the form of therapy used as with the stage of the disease when first diagnosed. Any woman who consults a physician should have a pelvic examination regardless of the presence or absence of pelvic symptoms.