1. In the previous paper of this series (Callow, 1949) a special method of graphical analysis was developed in order to calculate the effect of different rates of fattening on the percentages of fatty tissue, muscular tissue and bone, etc., in a carcass. This method has been used in the present paper to calculate the effect of different rates of fattening on the deposition of chemical fat and protein in the fatty and muscular tissues of a carcass during fattening.

2. The method of analysis depends (a) on the choice of an arch-type carcass on mathematical and biological grounds, and (b) the use of partition percentages for defining the proportions of fat, protein and water laid down in the fatty and muscular tissues during an increase in carcass weight due to fattening.

In Appendix I, Part II, of this series (Callow, 1948) some of the sheep dissected by Dr Wallace were referred to as Suffolk x Border Cheviot Crosses. This should have been Suffolk × Border Leicester-Cheviot Crosses.

1. Sixteen colchicine treatments, involving five main methods of application and six concentrations, have been used on Triticum interspecific crosses, Triticum—Aegilops intergeneric crosses and Agropyron—Triticum intergeneric crosses.

2. The efficacy of the major treatments in terms of plant survival, plant fertility and ear fertility has been compared, and the most successful method of application has been found to be absorption through the cut leaves—i.e. capping cut-back tillers with a small glass phial containing colchicine.

3. Fertility induced by colchicine is not complete. In plants producing grain, every ear is not necessarily fertile, nor are all spikelets in fertile ears usually fertile.

4. Evidence has been obtained of differential cross response to colchicine action, and also of cross-group response to particular treatments.

Some aspects of intervarietal crossing in Lolium perenne have been studied.

Using a number of experimental designs with non-red plants as the tester variety, results have been obtained as to the effects of isolation distance on intervarietal crossing.

In all cases contamination decreases rapidly, at first with increasing distance, but there is a progressive reduction in the rate of decrease produced by repeated increases in isolation distance. The actual rate of decrease varies with the number and arrangement of plots.

The effect of intravarietal pollen in reducing intervarietal crossing appears similar to that of distance in its mode of action. Within short distances from the contaminant, additional rows of intervening plants are highly effective in reducing contamination. This suggests that pollination within a population of plants occurs chiefly between neighbouring plants.

The flowering periods of the different strains of Lolium perenne and L. italicum overlap to varying degrees. Several early strains flower at the same time, e.g. British commercial, New Zealand Certified Mother Seed and Station-bred S24 perennial rye-grass; others, such as Kentish indigenous perennial ryegrass and strains of L. italicum, which are intermediate in date of flowering, overlap with both the early- and late-flowering strains.

Intervarietal crossing is considerably reduced when varieties which differ widely in date- of flowering are grown in close proximity to one another, but even in the case of extreme early and late strains some spatial isolation, or discarding of border rows, is necessary for maintaining varietal purity.

In certain instances when seed crops of early-flowering strains are endangered by late-flowering plants growing in adjoining leys, satisfactory isolation may be achieved through cutting back the contaminant crop just before flowering. When seed crops of late-flowering strains are grown alongside leys containing early-contaminant varieties, cutting back should be delayed until a few days prior to commencement of flowering in the seed crop.

The practical application of the results to grass seed production has been discussed. Existent isolation requirements appear not too great for grass seed crops intended for further seed multiplication, but for commercial seed crops the spatial isolation distance generally recommended may be reduced to 100, or even 50 yd., in the case of large fields.

1. There was no evidence that the higher body temperature of the chick, compared with other animals, conferred any advantage on it in the digestion of high melting-point fats, as exemplified by mutton fat.

2. The digestibility of linseed oil ranged from 95·0 to 99·9%. The highest digestibility observed for mutton fat was 88·1%.

3. The capacity to digest considerable quantities of linseed oil was rapidly developed in the chick. Adaptation to digest mutton fat was much slower.

1. Herring ‘alkali-reduction’ meal—a by-product from the alkali process of herring oil extraction—has been tested as a protein supplement for chicks.

2. At high levels of feeding it was toxic.

3. At low levels of feeding its nutritive value was low compared with other fish meals.

4. The method of manufacture of reduction meal destroys vitamin B12 and cystine, but supplementation of the material with vitamin B12 and cystine did not greatly enhance its feeding value.

1. The relationship between the soluble nitrogen content (soluble nitrogen/total nitrogen) of samples of dried silage and the pH of the corresponding wet samples has been investigated. It has been shown that a relationship exists between the two, and that when Ns/Nd is high the pH is low and vice versa. Moreover, the product Ns/Nd × d.m. is also related to the pH.

2. Again it has been shown that the ratio Ns/Nd bears a relationship to the digestibility of the silage as measured by the Wedemeyer Method in the laboratory. The potential usefulness of the ratio in this connexion is being further investigated.

1. Evidence, both direct and indirect, has been adduced to prove that the air is sufficient both qualitatively and quantitatively to supply all the nutritional requirements of plants, independently of the soil or soil bacteria.

2. The fertility of an undisturbed soil lies chiefly in the surface inch or two and is due to adsorption of plant nutrients from the air by organic and inorganic colloids, such nutrients being carried down to the roots of the growing crop by rain.

Since 1943 numerous multifactorial field experiments have been concerned with the development of methods for selective weed control in a variety of crops. Between 1943 and 1947 simultaneous comparisons have been made as to the relative effectiveness of sulphuric acid, cupric chloride, dinitro-o-cresol and the two growth-regulating substances—2-methy1-4-chloro -phenoxyacetic acid and 2:4-dichloro-phenoxyacetic acid—when applied as sprays (100 gal./acre) for the destruction of annual weeds in winter wheat.

There is a highly specific relationship between the weed species and the potential toxicity of any one compound. For the eradication of Ranunculus arvẹnsis and Scandix pecten-veneris, the two growth-regulating substances, as the sodium salts, are greatly superior, but for other species, such as Galium aparine, they.are wholly ineffective or only partially effective, e.g. Matricaria chamomilla. For Papaver rhoeas and Fumaria officinalis in the young seedling stage, sodium methyl-chloro-phenoxyacetate and ammonium dinitro-o-cresylate are equally toxic, while the indications are that Matricaria chamomilla and Centaurea cyanus are best killed with sulphuric acid or ammonium dinitro-o-cresylate. All these species are resistant or partially resistant to cupric chloride.

As a result of weed eradication, increases in grain yield ranging from 6 to 113% have been recorded, and over the twelve experiments the average increase for the most appropriate treatment was 23%.

At the concentrations employed for sulphuric acid (max. 18.4%) ammonium dinitro-o-cresylate (max. 1.1%) and cupric chloride (max. 4.0%) direct injury to the wheat, resulting in a loss in yield, has not been found when spraying is carried out in the active tillering stage. When spraying is unduly delayed, the yield depressions may be very considerable, more particularly with cupric chloride and sulphuric acid.

With the growth regulating substances, the results of two experiments indicated that the greatest selectivity is obtained when the concentration does not exceed 0.2-0.3% (2–3 lb./acre), but in the remaining trials no injury was observed up to a maximum concentration of 0.5%. In none of the trials was the formation of abnormal ears noted.

When mixtures of sodium methyl-chloro-phenoxy-acetate and dinitro-o-cresol are employed,. no significant interaction on crop yield has been found.

As part of a general programme for the development of new techniques of selective weed control, numerous experiments have been carried out during 1943–7 on the eradication of annual weeds from spring-sown oats and barley. These multifactorial experiments consisted essentially of simultaneous comparisons of the relative merits of sulphuric acid, copper salts, dinitro-o-cresol and the two growth-regulating substances 2:4-dichloro-phenoxyacetic acid and 2-methyl-4-chloro-phenoxyacetic acid. All the compounds were applied as aqueous solutions or suspensions at a spray rate of 100 gal./acre.

Within groups of compounds, cupric chloride is more toxic than cupric nitrate, and this in turn is more toxic than cupric sulphate to such weeds as Raphanus raphanistrwn. Similarly, dinitro-o-cresol or its ammonium salt is more effective than the sodium salt for the control of R. raphanistrum and Galeopsis tetrahit. There is some evidence that sodium methyl-chloro-phenoxyacetate is slightly superior to sodium dichloro-phenoxyacetate for the control of Galeopsis tetrahit and Sinapis arvensis.

Between groups of compounds, as long as the weeds are in the young seedling stage there is little to choose between sulphuric acid, cupric chloride, ammonium dinitro-o-cresylate and the growth-regulating substances for the control of Sinapis arvensis, Raphanus raphanistrum, Thlaspi arvense and Polygonum convolvulus when the concentration ranges for the four groups are respectively 9–18, 1–4, 0·4–0·8 and 0·1–0·4%. Within these limits of concentration P. persicaria is best controlled with sulphuric acid and Atriplex patula by dinitro-o-cresol.

In general, there is a decrease in the toxic effects with increasing age. There are however complex interrelationships between weed species, compound and stage of development. Whereas for cupric chloride its effectiveness against Sinapis arvensis is little changed between the cotyledon and flowering stage there is with flowering a marked falling off in the efficiency of sodium methyl-chloro-phenoxyacetate. In the intermediate phase of development the growth-regulating substances are most toxic to Raphanus raphanistrum.

The results for crop yield demonstrate that sulphuric acid and cupric chloride are less selective than dinitro-o-cresol or the substituted phenoxyacetic acids, since for equivalent degrees of weed control smaller increases in grain production have often been recorded. These injurious effects are maximal at the higher concentrations and when spraying is delayed until after tillering is completed. There is a similar age trend for dinitro-o-cresol and the two growth-regulating substances, and in the case of the latter some indication of a concentration effect, i.e. the compounds are most selective at concentrations of 0·2% or less.

For the twenty experiments in which the yields were recorded the most appropriate herbicidal treatments have resulted in gains in yield over the controls ranging from 0·4 to 82·2% with a mean of 23·8.

The visual method of assessing the quality of semen, in use at Artificial Insemination Centres, has been compared with assessments based on measurements of impedance change frequency (I.C.F.) on the same samples. Analysis of the results shows that I.C.F. measurements could probably be substituted for visual assessments at A.I. Centres, without conception rates being adversely affected.

1. At two centres, Hillsborough and Shinfield, forty-eight pigs in four groups were fattened on rations containing Australian sorghum. The control ration consisted of 30%, wheatfeed, 30% barley meal, 30% maize meal and 10% fish meal. In the three experimental rations either barley meal or maize meal or both were replaced by sorghum.

2. The rations containing 30% of sorghum proved to be equal to the control ration as far as live-weight gain of the pigs and the efficiency with which they utilized food was concerned. When 60% of the ration consisted of sorghum there were indications that both rate of gain and food utilization suffered.

3. Some aspects of carcass quality suffered when either sorghum alone or sorghum plus maize formed 60% of the ration. The quality of the control carcasses, although quite good by present-day standards, would not qualify for first grade when commercial grading is re-introduced.

4. Bacon produced on rations containing up to 60% sorghum had no off-taste or unpleasant flavour.

5. In general, the value of sorghum in the ration of fattening pigs was found to be about equal to that of maize.

1. The lignin and cellulose contents of the dry matter of seven herbage species, including three grasses, two legumes and two herbs, have been determined at different stages of growth. Similar analyses of large samples of crude fibre isolated from early and late cuts of all species were made.

2. No considerable differences between the lignin contents of the dry matter of the species were found when comparisons were made at the same stage of growth.

3. In a majority of the species examined a marked rise in lignin content was found to occur at the flowering stage.

4. The cellulose content of grasses, whether expressed as a percentage of the dry matter or of the carbohydrate fraction, is much higher than that of either legumes or herbs. In consequence, crude fibre contents are greater in the former than in the latter.

5. The findings of earlier workers that the composition of the crude fibre varied as between species have been confirmed. It has been shown that, in any one species, the crude fibre make-up is dependent on the stage of growth.

6. The recovery of lignin and cellulose in the crude fibre of the different species has been studied. Several possible explanations of the variable recoveries found have been suggested and discussed.

7. The case for modification of the conventional method of feeding-stuff analysis, as it applies to the non-fatty and non-nitrogenous organic matter, has been discussed in the light of conclusions reached in the course of this work.

A review of published work emphasizes the existence of a fundamental relationship between the quantity of milk and butterfat per cent. This general relationship may be stated thus: as the quantity of milk increases, the quantity of fat increases also, but at a slower rate. Therefore, the fat per cent, or concentration, falls as the volume of milk increases.

1. An investigation has been made of the structure, distribution and dimensions of the so-called sweat glands in twenty-one different body regions of each of five 3- to 4-year-old Ayrshire cows, and incidental studies have been made on calves and embryos.

2. It has been observed that in all those regions each hair follicle is accompanied by an arrector pili muscle, a sweat gland and a sebaceous gland. This combination has been designated a ‘hair follicle unit’.

3. In the skin of embryos the sweat gland appears as a single unbranched tube and in the skin of calves and cows it is a bag-shaped gland with a long slender duct which opens on the skin surface as a funnel-shaped outlet.

4. The gland is composed of two layers of cells, an outer myoepithelium and inner glandular epi thelium.

5. What may be successive stages in the intraluminal transformation of the secretory products discharged by the gland cells lining the lumen, are illustrated by a series of photographs.

6. The glands have a poor blood supply and appear to be apocrine. It is unlikely, therefore, that the sweat glands of Ayrshire cows function as effectively in heat regulation as human sweat glands.

7. The number of sweat glands per sq.cm. of skin was measured in all the regions. The average number was 1871 per sq.cm., ranging from about 1000 in the lower limbs to about 2500 in the axilla and neck regions.

8. The length and circumference of the gland were measured, hence its secretory surface was calculated. The average area of secretory surface of a single sweat gland was 0·22 sq.mm., while the average area of secretory surface of the sweat glands per sq.cm. of skin was 3·94 sq.cm. There was a significant negative correlation between the number of glands per sq.cm. and the area of secretory surface of a single sweat gland.

9. The ventral region of the neck, the axilla and upper hindleg had the largest area of secretory surface per sq.cm. of skin, while the forehead, back (sacral), gluteus, lower foreleg and hindleg had the smallest.

10. The only region which had a significantly smaller area of secreting surface than the front flank region was the sacral region of the back.

1. The attraction between spheres, due to surface tension forces, in a lenticular drop between them is calculated for spheres in contact and at increasing separations up to the point of rupture of the drop. Hence the work of separation of the spheres is calculated.

2. Experimental measurements confirm the validity of these calculations, down to very small drop sizes, where it is likely that the failure is in the experimental method. As predicted by Fisher, the force decreases with increasing drop size, while the work of separation increases. Since, however, it is shown that the smaller lenticels are more easily ruptured, no discrimination is provided between the differing explanations of Haines and Fisher of measurements made with the Atterberg apparatus for measurement of soil cohesion.

An experimental verification of the validity of Fisher's calculation of the pressure deficiency inside the drop is also given.

3. It is pointed out that these results depend on the geometry of the system; types of contact other than that of spheres will show different behaviour. Hence generalizations about the behaviour of a real soil, based on an idealized soil of packed spheres, may lead to erroneous conclusions.

1. A gradually decreasing plane of light and increasing plane of darkness is not an essential factor for stimulating the onset of oestrus in sheep.

2. Sheep being short-day breeding animals, a standard and regularly maintained rhythm of short-light and long-dark will stimulate the onset of oestrus.

3. The terms short and long are used in the relative sense only, since their significance is solely a means of supplying the necessary contrast impulse to the pituitary gland.

4. A ratio of 1 part of light to 2 parts or more of dark is sufficient to supply the contrast effect.

5. Oestrous cycles induced by artificial light rhythms appear to be normal in all respects, con forming to the normal intervals between heat periods and associated with the ovulation of normal ova.

6. The anoestrous period varies in depth, and sheep which have just entered it may be brought back into oestrus very much faster than animals which are in deep anoestrum.

7. The milk yield of lactating ewes does not appear to be unduly depressed by the onset of oestrous periods induced by an artificial light-dark rhythm.

The genitalia of a control series of nineteen animals, slaughtered for other reasons than reproductive failure, were studied. Of these six were in various stages of pregnancy, one was in a ‘proliferative phase’, being slaughtered probably just before the first oestrus after calving, and twelve represented different phases of the oestrous cycle, more than half exemplifying the last 4 days before heat. Stages were judged from the appearance of the ovaries, and checked in five instances by repeated rectal examinations, and observation of behaviour during life. Of the nineteen uteri eight yielded bacteria on culture, sometimes in moderately high density; from two of them, pure cultures were recovered respectively of Pseudomonas and Neisseria catarrhalis; and in another, probably Proteus was found. No previous records of these three genera at such a site have been found. Only aerobic blood agar plate cultures, and those for tuberculosis organisms were made. Dissection results unequivocally supported the view of Tagliavini in opposition to that taken by Hammond, that the sanguineous elements in post-oestral discharge originated from endometrial extravasation. The cow slaughtered 4 days after heat indicated that congestion disappears from the caruncles before leaving the areas between them. Microscopically, no mast cells, as observed by the Italian workers, could be seen; it appeared that a ‘proliferative phase’ occurs in every cycle during the three pre-oestral days, when gland tissue proliferates from its nadir of development, surface epithelium grows in height, and vascularization progresses. The rate and interrelations of these changes seemed variable. Arterioles appeared to be withdrawn from the superficial mucosa during the secretory phase. Tagliavini's claim to have observed sloughing of epithelium about the 17th day, strictly equivalent to the process of menstruation in the Primates, must on the evidence be regarded with considerable reserve.

The cellulose isolated by the method of Druce & Willcox (1949 a) has been examined by a hydrolytic procedure. The results confirm the high ‘hexosan’ content of the residues.

The recovery of ‘hexosan’ from ‘bran cellulose’ has been shown to be very low (58%), and it has been demonstrated that the presence of large amounts of phytic acid is not responsible for this. It is suggested that ‘bran cellulose’ contains components which do not yield reducing sugars on hydrolysis.

The results of two sets of soil nitrate measurements on the three-course rotation plots at the Gezira Research Farm are described. The first set is a long-continued series taken over 21 years; it shows for the first foot samples that there is a distinct tendency for nitrates to be depressed during the rainy season, this tendency being more marked in the more open rotations. This is ascribed to washing down of nitrates. The second set of measurements shows accumulations in the second foot and a distribution consistent with downward movement.

In the Sudan Gezira the yields of irrigated cotton are positively correlated with the amount of rainfall in the 6 weeks before sowing. It follows from the work described here that this is not due to increased nitrate in the top foot of soil at sowing time.

The sampling of this experiment for nitrate was started by my predecessor, H. Greene, and continued by O. W. Snow. The field experiment itself has been conducted by the Plant Physiology Section of the Research Division of the Ministry of Agriculture.