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1. 1. In thin-layer chromatography milk fats of fifteen species of ruminants exhibited two distinct triglyceride spots, those of forty species of non-ruminants only a single spot. 2. 2. The faster-moving triglycerides in ruminant milk fats had higher contents of 18 carbon acids and were devoid of butyric acid. The palmitic acid contents of the two groups of triglycerides were nearly identical.

1. The nervous activity in single afferent gastric vagal units was recorded electrophysiologically from halothane-anaesthetized sheep with spontaneous reticulo-ruminal movements present.2. Sixty-six afferent units innervating gastric mechanoreceptors were isolated from fifteen sheep. The receptors were located mainly in the medial walls of the reticulum and the cranial sac of the dorsal rumen, and also in the reticular groove, the reticulo-ruminal fold, the dorsal and ventral sacs of the rumen and the omasal canal.3. The mean conduction velocity (C.V.) for twenty-seven units was 12.4 +/- 1.0 m/sec (S.E.). For units with a pathway in the dorsal vagal trunk, the mean C.V. was 14.5 +/- 1.0 m/sec (S.E.) and for units with a pathway in the ventral vagal trunk the mean C.V. was 6.6 +/- 0.5 m/sec (S.E.).4. From the receptors a slowly adapting response was elicited by tangential lengthening. These were tension receptors in series with contractile elements, as they were excited by increased tensions developed both passively by inflation of the viscus and actively by muscular contractions.5. Receptors in the reticulum and the rumen appeared to be situated deep in the muscle layers, whereas those in the reticular groove structures seemed to be more superficial and gave the in series tension receptor response as well as a response to light pressure.6. A resting discharge in tension receptor units was usually absent at low levels of distension but appeared and increased as the level of distension was raised. Intermittency and fluctuations in the resting discharge were related to intrinsic local movement involving the receptive fields. Increasing distension enhanced the intrinsic movements.7. Even after the removal of the abomasum, reticular and ruminal (primary cycle) movements were evoked by distending the reticulum. It is possible that this manoeuvre enhanced intrinsic movements, which, in turn, caused an increased excitatory afferent input to the ;gastric centres' from in series reticular tension receptors.8. The enhanced afferent discharge from reticular tension receptors elicited by an isometrically recorded reticular contraction reflexly inhibited the subsequent (primary cycle) contraction of the rumen.9. Very few receptors were located in the caudal regions of the rumen whereas the cranial sac is richly supplied with tension receptors. The idea that the cranial sac may serve as the reflexogenic zone for secondary cycle movements of the rumen is discussed.

1. The technique for the quantitative estimation of lignin by digestion with 72% H2S04has been investigated. Two methods of pretreatment designed to eliminate interference products of carbohydrates and proteins were compared, namely (a) acid and pepsin and (b) acid detergent. The latter technique gave low lignin yields owing to the colloidal dispersion of lignin in the acid detergent treatment. Erroneous results arise from an inadequate digestion in 72% H2SO4. It was found preferable to filter the product lignin without prior dilution of the acid since white particles of material, assumed to be cellulose, flocculated from solution on dilution. Also there is some loss due to colloidal dispersion of lignin during refluxing in dilute acid.2. Analysis of soda lignin and sulphuric acid lignin preparations from hay, duodenal contents and faeces of sheep with exteriorized flow through a re-entrant duodenal fistula provided evidence for the degradation of lignin by digestive processes. Demethoxylation of lignin occurred mainly in the stomach, suggesting that this was the main site of breakdown.3. A new displacement method of measuring duodenal flow is described. Quantitative results obtained also indicate that lignin is degraded mainly in the stomach to the extent of about 10%.4. These results suggest that faecal lignin is an adequate marker for the estimation of duodenal flow, and hence of the extent of changes in the stomach and intestines respectively.

A method of preparation of the ruminant stomach is described that allows it to be sectioned longitudinally to reveal the structural details of the rumen and reticulum on one side and the omasum and abomasum on the other side.

L'injection i.v. de 6 µg/kg de gastrine synthetique (ICI 50 123) est suivie, chez les herbivores ruminants, malgre une inhibition prolongee de la motricite rumino-reticulaire, d'une importante contraction de l'omasum (feuillet). La reponse excito-motrice persiste apres atropine et semble specifique du feuillet qui equivaut, sur le plan embryologique, a la partie moyenne de la petite courbure de l'estomac.

IN order to investigate the mechanical aspects of digestion in the ruminant stomach, pressure variations occurring within the reticulo-rumen have been measured on many occasions1–3, using balloons connected to liquid-filled manometers or to recording tambours. Wester1 reported that the intra-ruminal pressure in the cow showed phasic fluctuations of 2.5 cm. mercury, while Quin, Van der Wath and Myburgh2 recorded a maximal rise of 10.0 cm. water in the sheep; in both instances the basal intra-ruminal pressure was close to atmospheric pressure. Balch, Kelly and Heim3, using a balloon connected to a writing tambour, recorded pressure-changes from within the reticulum of the cow and showed a basic level of 2.5–3.5 cm. mercury above atmospheric pressure rising by 1–2 cm. mercury with contraction of the reticulum. It is probable that in the latter case the higher resting pressure is due to the hydrostatic effect of the liquid contents of the reticulum.

Formaldehyde has been used to protect proteins and lipids from metabolism in the rumen, and the present studies were designed to investigate the metabolism of [140]formaldehyde when given to ruminants as an aldehyde-casein-oil complex. Approximately 60-80% of the consumed [140]formaldehyde was metabolized to carbon dioxide and methane, a further 11-27% was excreted in the faeces, and 5-6% was accounted for in the urine. The amount of radioactivity excreted either in the expired air or faeces appeared to be dependent on the length of the reaction time between the aldehyde and casein prior to feeding. Small amounts of 140 radio� activity were detected in body tissues and milk, but this was not present as formalde� hyde. It is concluded that ruminants effectively metabolize formaldehyde and there is no accumulation of this compound in the carcass or milk.