The galactan preparations were made as described in detail for galactan F by Hudson et al. (1967) except that the Sephadex G200 column formerly used (80 x 270 mm) was replaced with one 50 x 1000 mm, and that a pneumatically-driven Padberg supercentrifuge was used instead of a steam-driven Sharples supercentrifuge. Three batches of galactan F were made; these were identified as LS30, LS31, LS32. In the case of LS31 the supernate of the culture was heated before and not, as with LS30 and LS32, after acidification with glacial acetic acid; in other respects the procedures for preparation of the three batches were identical.Control solutions. Uninoculated culture medium (BVFOS) of the same type as that used in the preparation of galactan F was subjected to the same extraction procedures as those used for preparation of the galactan. This provided one of the control solutions injected intravenously into calves. The other control solution used was the 0.85% (w/v) NaCl in which freeze-dried galactan preparations were dissolved for intravenous inject ion.Testing for pyrogenic activity. This was done in conscious rabbits (2-6-3.3 kg) by the method described in the British Pharmacopoeia (1968) except that two rabbits were used for each preparation and rectal temperatures were monitored continuously with a thermistor probe (Yellow Springs Instrument Co., Yellow Springs, Ohio).Chemical analyses. Quantitative amino-acid analyses of the galactan preparations were made after hydroiodic acid hydrolysis (Inglis, Nicholls and Roxburgh, 1971). The method has been found suitable for preparations of high carbohydrate content (Nicholls and Inglis, personal communication). Total percentage of protein was calculated as the sum of the individual amino-acid contents of the preparation.Animal experiments. Most of the experiments were done on 41 calves that were 10-12 weeks old, and weighed 30-90 kg. They were of the Jersey, Hereford and Friesian breeds and crosses of the Jersey and Friesian breeds; the majority were females. All had been taken from their mothers 4 weeks before the experiments and were being maintained on reconstituted skim-milk powder and calf-concentrate pellets. All had begun ruminating. Experiments were undertaken both in conscious and anaesthetised calves.The experiments on conscious calves were done with the animals standing in a stall, or restrained in lateral recumbency on a table to minimise movement artefacts in electrocardiograms. A venous cannula (Bard, International Ltd, Sunderland) was introduced into one or both jugular veins, and in some experiments a polythene tube was introduced into the pulmonary artery, being passed from the right jugular vein via the right atrium and ventricle. The pressure profiles recorded from these saline-filled tubes on pressure transducers were used to identify the final sites of the tips of the cannulae and verification was obtained at necropsy. Standard limb leads were used, and recordings made of either lead I, I1 or I11 of the electrocardiogram (ECG). Respiratory movements ...

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