The Ixodidae have received so little consideration at the hands of British naturalists that there does not exist amongst our literature any classification of the family having pretension to accuracy or completeness. This may be sufficient to account for the fact that in 1900 when inviting correspondence through the columns of Science-Gossip, I did not receive any reply from a fellow-countryman who had made a serious attempt to study the British ticks, though I have been favoured with much kindly assistance from correspondents who had turned their attention to foreign species.

1. The amounts of wood shavings eaten by a group of unmuzzled calves allowed unlimited access to the shavings but fed otherwise only on milk were estimated by a lignin ratio technique. The amounts increased to a mean value of about 250 g. dry weight/day at 13–14 weeks of age.

2. Although a marked decrease in net magnesium absorption from the diet occurred with age in a group of efficiently muzzled milk-fed calves the mean decrease was not as great as that in the group of unmuzzled calves when the latter were eating considerable amounts of wood shavings. Data are presented which show that the difference is accountable by the excretion in the faeces of some of the magnesium in the increased flow of endogenous fluid from the rumen (probably mainly saliva) in the unmuzzled calves. The results suggest that many milk-fed calves (assuming about 11–12 mg./100 ml. magnesium in the milk) will resist hypomagnesaemia for at least 5 months but only if they are effectively prevented from chewing foreign matter. This may partly account for previously observed variations in. the ages at which calves develop hypomagnesaemia.

3. Net calcium absorption from the diet decreased with age in both the muzzled and unmuzzled groups of calves but again to a greater extent in the unmuzzled group. The difference was much greater than could be accounted for by increased loss of endogenous calcium due to greater saliva production in the unmuzzled calves. It appeared that the shavings contained a factor (not phytate) which interfered with calcium utilization. It is suggested that the factor might act by inhibiting the action of vitamin D.

The results are described of twenty-two experiments carried out on the feeding of bacon pigs at different centres throughout Great Britain, in the course of which nearly 400 pigs were fed according to three different scales of rationing. All the pigs were fed on the same scale until reaching 100 lb. live weight, when they were eating 4 lb. of meal per head per day. From this stage three different levels of feeding were followed; in each case the daily allowance reached a maximum when the pigs were 170 lb. live weight. The amounts being fed were then: 7 lb. 8 oz., 6 lb. 5 oz. and 5 lb. 3 oz. per head per day respectively.

1. A small-scale plot experiment was conducted at the Hannah Institute for the 3-year period 1963–65, to study the comparative effect of applications of various mixtures of dung and urine (slurry treatments) on the yield and quality of an established S23 ryegrass and S100 white clover sward.

1. The effects of age of ewe, and year, sex and type of birth of lambs on lamb weights between birth and weaning were measured and appropriate correction factors estimated in a flock of East African Blackheaded sheep maintained over an 11-year period in Western Uganda. These correction factors were then used to examine the effects of a long dry season at different stages of lamb growth.

2. On birth weights the effects of sex ranged from 0-25 lb. to 0-40 lb.; twinning 1-0 lb.; gimmer's lamb 0-5 lb. On 2-month weights the corresponding adjustments were 0-2 lb.-l-4 lb.; 5-1 lb.; 1-7 lb. On weaning weights 0-3 lb.-2-9 lb.; 6-0 lb.; 2-6 lb.

3. A long dry season during late pregnancy did not appear to affect lamb birth-weights and a dry season between 2 months and 5 months of age did not affect lamb weaning weights. However a dry season during the main suckling period from birth to 2 months of age significantly lowered lamb weights at 2 months of age.

An experiment, carried out to determine the effect of dressings of sulphate of ammonia on an established lucerne-cocksfoot ley grown in narrow rows on heavy gault clay soil, is described and the results discussed. The experiment was carried out over 3 full years (1948–50) and the first crop of the following year. The results suggest that it is possible to increase the yields of grass and total produce without decreasing the yield of lucerne but that no marked increase in the yield of nitrogen per acre is to be expected. Of the times of application tested February proved the most effective.

Cultivated tomato has a narrow germplasm base because of several population bottlenecks in the form of founder events, as well as natural and artificial selections that occurred during domestication and evolution of modern cultivars. The F2 of commercial single-cross hybrids, as well as locally well-adapted varieties, provide germplasm for developing recombinant lines and exploiting genetic variability, respectively. The present study aims to discriminate the breeding value of tomato source material, i.e. commercial hybrids or well-adapted varieties, by (i) estimating tolerance to inbreeding of hybrids or estimating heterosis of diallel hybrids between varieties, (ii) determining undesirable traits and (iii) determining general combining ability (GCA) and specific combining ability (SCA) effects from diallel crosses between hybrids and between varieties. Two hybrids and four varieties were assessed. One hybrid showed 0·03 inbreeding vigour, which was not combined with undesirable traits in the F2 generation. However, negative GCA and positive SCA values did not support the hybrid as source material, provided that hybrids with low inbreeding depression, positive GCA and negative SCA correspond to an F2 capable of developing recombinant lines. The assessment of the varieties showed positive GCA and 0·34 heterosis in one variety, indicating agreement between yield and GCA, and that high-yielding varieties may produce high-yielding hybrids. In conclusion, the proposed mating design, taking into account the tolerance to inbreeding for hybrids and the heritability of general worth for both resources, provides a mechanism for ensuring continued improvement in plant performance through plant selection programmes.

An experiment was carried out, using Duroc Jersey barrows, to test the hypothesis that relationships within the pig fat-free carcass remain unaltered when varying the principal dietary factors: energy, protein or both. Twelve pigs were assigned to each of the following diets: high energy-high protein (HEHP), used as control group; low energy-high protein (LEHP); high energy-low protein (HELP) and low energy-low protein (LELP). From 30 kg live weight onwards the animals were individually penned and fed once a day the experimental rations, on a restricted scale of feeding related to live weight. Compared with the control group, daily intake of metabolizable energy was approximately 37% lower in LEHP and LELP groups while daily protein intake was approximately 25% lower in HELP and LELP groups.

In each group the 12 pigs were slaughtered between 60 and 110 kg. The right half carcasses were completely dissected using strictly anatomical criteria. The main growth characteristics of the four treatments were described by second degree polynomials fitted to the live weight-age data. Each treatment produced a characteristic growth curve. In every case significant differences were found in the polynomial coefficients. Data on body composition were subjected to analysis of covariance, using the linear model y = a + bx. When growth of different parts of a whole were studied the weight of that whole was used as the independent variable. When muscle:bone ratio was examined the weight of total side muscle was used as covariate in the covariance analysis for total side bone.

The major treatment effects were on the relationship between fat and non-fat tissues in the carcass. Thus, in relation to dissected side weight, HELP animals had more fat and less muscle and bone than controls, while LEHP and LELP pigs had more muscle and bone and less adipose tissue. Within the fat-free carcass several differences were found on muscle weight distribution. LEHP, HELP and LELP pigs had a higher proportion of ‘expensive muscles’. However, the magnitude of these changes was small and likely to be of little commercial importance. On the other hand, only minor differences were found in bone weight distribution. These were confined to the scapula and femur. Muscle:bone ratio was not affected by the treatments. Within the adipose tissue differences were observed in growth rates from the different depots relative to total side fat. Thus, it would appear that the growth rate of the subcutaneous depot was higher and that of the intermuscular one lower in LEHP and LELP animals. The body cavity depot was less in these animals.

Twenty-four multiparous female South African indigenous goats were used. Once a week during the 2nd (weeks 8, 11 and 14) and 3rd (weeks 18, 19 and 20) trimesters, between 08·00 and 15·00 h, four females per treatment were randomly selected and observed every 1 min for time spent grazing, browsing, ruminating and idling. Blood samples were taken once a week during the 2nd (weeks 8, 11 and 14) and 3rd (weeks 18, 19, 20 and 21) trimesters for measurements of some mineral elements and protein metabolites. Goats on natural pasture (NP) grazed 54·8 min (P<0·001) more and browsed 53 min (P<0·001) less than goats on Leucaena leucocephala-grass pasture (LGP) during the 2nd trimester. During the 3rd trimester, goats on NP treatments grazed and idled more (24·7 min, P = 0·004; 15·8 min, P = 0·044, respectively) but ruminated less (−24·1 min, P<0·001) than LGP goats. Time allotted to each field activity by the goats on both treatments within trimester seemed to be dependent on forage species composition while activity between trimesters was possibly influenced by seasons, plant type, herbage quantity, environment and quality, and changes in stage of gestation of the goats. Blood Mg level on NP was higher (P = 0·051) than on LGP during the 2nd trimester while blood Cu and albumin contents on LGP were significantly higher (P = 0·029 and 0·022, respectively) than on NP during the 3rd trimester. Furthermore, blood concentrations of the haematological parameters (except serum protein) on both treatments were within the normal range for goats in the tropics and subtropics and perhaps explain the absence of mineral and nutrient deficiency symptoms. The absence of visible symptoms of mineral deficiency and mimosine toxicity in LGP goats can be attributed to the transfer of DHP-degrading rumen bacteria. The bacteria effectively detoxified mimosine and its metabolites, thereby overcoming chelating tendency of mimosine and its metabolites. Mimosine-susceptible pregnant SAIG can be safely grazed on LGP once their rumen is completely colonized by the DHP-degrading rumen bacteria (Synergistes jonesii).

Three rates of phosphate (0, 25 and 60 kg/ha P2O5) were applied for 7 years to phosphate-deficient grassland at Tel Hadya, north Syria. Liveweight, milk yield, wool production and supplementary feeding of Awassi sheep were monitored for six seasons (1985/86 to 1990/91). The experiment was grazed at low (0·8 sheep/ha per year) and high (1·7 sheep/ha per year) stocking rates from the second to the fourth season, while in the fifth to seventh seasons stocking rates were increased to 1·1 and 2·3 sheep/ha per year, respectively. The experimental site was typical of communally owned, degraded grasslands within the cereal zone of west Asia, where cropping is not possible because of shallow, stony soils and steep slopes.

The results showed that annual applications of phosphate, even at 25 kg/ha, improved pasture and sheep productivity. Liveweights were higher on fertilized plots in five out of six years, significantly so in the last three. Milk production was also higher on phosphate-treated plots, and the need for supplementary feeding was reduced, especially in the last three years, when rainfall was below average. The results suggest that stocking rates can be significantly increased by annual applications of small amounts of superphospate, and that doing so is profitable.

Use of the results depends on the presence of native legumes, the level of soil phosphate, and the ability of farmers to control grazing of these communally owned grasslands. A strategy to fulfil these criteria is suggested.

The effects of exchangeable sodium on emergence, growth, development and yield composition of oilseed rape were investigated at Buenos Aires, Argentina in 1992. A pot experiment was performed using five exchangeable sodium levels, expressed as Sodium Adsorption Ratio (SAR: 12, 20, 27, 34 and 44). Soil with nine different exchangeable sodium contents (SAR from 0·5 to 50) and seven different particle size distributions (from sandy loam to clay) were used in a parallel trial to study the effect of soil crusting on oilseed rape emergence. Soil crusts were made using a rainfall simulator after seeds were sown. Both experiments showed that the direct effect of sodium on emergence occurred with SAR values higher than those which caused clay dispersion (SAR > 20). Oilseed rape seedlings could penetrate crusts having a resistance of < 230 kPa. At SAR values > 20, main stem growth and yield decreased significantly (P < 0·05). These reductions were counterbalanced by an increase in the number of secondary stems. At SAR levels > 34, stem number, grain number per pod on the main stem, as well as pod number on both main stem and secondary stems, were reduced, leading to a marked reduction in total yield. The most important agronomic effect of soil sodium on oilseed rape would be at emergence stage, due to soil crusting.

1. An attempt was made to verify a report that mixed samples of bull semen show better motility and survival than their unmixed controls.

2. The claim was not confirmed; in 83 of 104 samples the motility score of the mixed sample was less than the score for the better individual constituent sample.

A radiography unit was developed with which two technicians and two assistants were able to diagnose number of foetuses in 400–600 ewes per day on farms. Diagnoses made between 100 and 120 days of gestation in flocks where weekly mating records were made were 95–98% accurate as judged by lambing records. In most flocks more than 90% of twin pregnancies were correctly diagnosed. Agreement between diagnoses and lambing records was reduced when weekly mating records were not available. The radiographic examination had no detrimental effects on ewes or lambs.

Following three differing pre-stress temperature treatments, potted plants of three populations of Festuca arundinacea, syn. 1 and syn. 2 (North African) and S. 170 (British) were subjected to a cold stress of 20 h at – 8 °C in a growth cabinet.

In all populations, survival was greatest when the cold stress followed continuous low temperatures for 2 weeks, was intermediate after part-day low temperatures for the same period, and poorest after continuous warmth. The hardening response, especially after the fluctuating regime, was greater in S. 170 than in either syn. 1 or syn. 2, between which little difference was detectable.

There was no overall difference in survival between spring-sown and autumn-sown material, nor any apparent relationship between survival and relative growth rate.

In a further trial, the same three populations were subjected to differing periods of cold stress at — 9 °C-single exposure for 12 or 18 h periods, or one, two or three 6 h periods.

The synthetics were progressively weakened by repeated stresses, and were almost completely killed out by 12 or 18 h exposure. Differences in mortality following short and longer periods of exposure were associated with differences in soil temperatures.

(1) Rather over 50 per cent, of the cows in this country probably possess accessory or supernumerary teats, the number of which varies from one to three.

(2) In many cases at any rate, these teats are associated with additional glands.

(3) These additional glands are frequently functional and secrete milk.

(4) Ordinarily this milk is absorbed into the circulation, the lactose being secreted in the urine.

(5) The presence of active accessory or supernumerary glands is an undesirable characteristic since it involves the formation of milk which is not utilised.

The effects of part, age and species of plant and some soil characteristics on the relationships between (a) sum of the cations (Σ cations)–% total N and (b) ratio of sum of the cations sum of the anions (R)–% organic N relationships in crops were tested in four experiments in the glasshouse. Crops were grown in soil and given four or five amounts of N03-N and sometimes a uniform dressing of other nutrients.

Results confirmed that there was a positive linear relationship between S cations in plants and their % total N when N03-N was supplied and the proportions of cations and anions entering roots from the soil solution (R values) were not constant but were in some way related to the elaborated nitrogen status of the plant, suggesting they may be linked with nitrogen metabolism. The cation-anion relationships were of the same general type regardless of the part of the plant that was analysed, its age or species, or of the type of soil in which it was grown. Analysis of leaves adequately reflects relationships in whole plants. Although the relationships had the same form with all species, dicotyledons had greater Σ cations and R values than monocotyledons at equal % total N and organic N respectively. Within the group of relationship curves obtained with different soils, at equal % total and organic N, 2 cations and R values were greater in grass grown in alkaline than in acid soil. Soil properties that affect the proportions of NH4-N and N03-N presented to plant roots probably have an important influence on the relationships. These cation–anion relationships in crops were not changed when yields varied greatly.

Twenty-one elite sorghum lines were assessed for resistance to foliar, peduncle, rachis, grain and overall panicle anthracnose under natural infection at Samaru and Bagauda in 1996 and 1997. Three genotypes (R 6078, IS 14384 and CCGM 1/19-1-1) were completely resistant to all forms of the disease while Nagawhite was completely resistant to foliar, peduncle and rachis but moderately resistant to panicle anthracnose. The data indicate vertical disease progression from leaves onto peduncle and the rachis. More genotypes were susceptible to grain than rachis anthracnose thus indicating that grain infection could be direct or through vertical progression and direct pathways.

Field experiments explored the relationship between canopy apparent photosynthesis (CAP) and grain yield and examined the effect of plant population density on CAP. Two cultivars of wheat were grown at five plant population densities in 1986 and 1987 in Taian, China. Measurements of CAP were made at intervals during the growth period by placing a large plastic-covered chamber over a 0·7 m2 segment of the canopy and measuring CO2 depletion with infra-red gas analysers for 1–2 min at c. 25 °C around noon when solar radiation was > 1100 umol/m2/s. Canopy respiration (CR) rates were measured by covering the whole chamber with a black screen in the daytime. Calculations of CAP and CR were made using the chamber volume, air temperature and changes in CO2 concentration over time and expressed on a land area basis.

Maximum values of CAP and CR were 4–6 g and 2–3 g CO2/m2/h, respectively, at the anthesis stage, decreasing with age during grain filling. The decrease was more rapid at the high than at the low population density. The difference in CAP between plant densities before booting and after anthesis could be attributed to reductions in leaf area index (LAI) and photosynthetic rate.

Grain yield also differed between plant population densities, the range being from 5250 to 7500 kg/ha in both years. Grain yield and 1000-grain weight were positively correlated with CAP during grain filling (r = 0·78 and 0·99, P < 0·01, 8 D.F.). Effects of plant density on CR were highly significant, but CR was not related to yield (r = 0·50).

Quantity/potential relationships, between gain and loss of K by the soil and K potential (RT In ακ/⊧αca+Mg) were determined on twenty-seven Rothamsted and Woburn soils. K extracted by neutral N ammonium acetate, by H-resin and 0·5 M sodium bicarbonate (pH 8·5) were also measured.

The ability of an extractant to remove soil K is equated to a K potential (derived from the quantity/potential curve) which the soil attains on removing K equal to that taken out by extractant. Mean values for all soils were – 4995 ± 97 cal/equiv for the ammonium acetate, – 6081 ± 88 cal/equiv for the H-resin and – 4336 ±117 cal/equiv for the sodium bicarbonate extractants. For the first and last extractants the ability to remove K was less in rich than in poor soils.

Varying the ammonium ion concentration from 0·1 N to 1 N in ammonium acetate/acetic acid mixtures, N in acetate ions, did not greatly affect their ability to remove K.

When etiolated seedlings of maize and cowpea were subjected to a heat stress of 45 °C for 8 h and subsequently illuminated, there was a retardation in the rates of leaf elongation and chloroplast formation, but the rate of increase in dry weight was not affected. However, a heat stress of 45 °C for 16 h decreased all the three rates measured, the effects being more pronounced with the longer duration of stress in the case of leaf elongation and chloroplast formation. The cowpea seedlings were more sensitive to heat than the maize seedlings. The decreased yield (dry weight) in the 16 h treatment was due, at least partly, to the heat-induced retardation of the growth of the photosynthetic apparatus.