1. A femur was analysed from each of the following malnourished children: five Turkish (4–7.5 months; marasmic), eight Jamaican (9–13 months; two marasmic, one marasmic with kwashiorkor, three with kwashiorkor, two ‘malnourished’) and two Ugandan (11 and 12 months; marasmic and with kwashiorkor respectively). These were matched with appropriate controls. Dry weight, fat, total nitrogen, collagen N, calcium and phosphorus were determined, and values are presented for them in the bone, with and without epiphyses, and in the epiphyses and cortex.

2. The femurs of the Turkish children (4–7.5 months) showed greater deficits in length, Ca and P than did those of the Jamaican and Ugandan children (9–13 months). In both age-groups, regardless of the clinical condition, there was significantly less dry fat-free bone tissue than in control bones of similar ages. The concentration of fat in the bones was variable, but in the Turkish bones it was higher than in the controls.

3. When the epiphyses were excluded, the femurs of the Jamaican and Ugandan children with kwashiorkor contained a lower concentration of total N per 100 g fat-free solids than did those of children with marasmus.

4. The epiphyses of the malnourished children aged 4–7.5 months contained lower concentrations of total N, collagen N, Ca and P than those of controls. In the older age-group the only significant difference was a lower level of Ca.

5. The cortex of all the malnourished children had a similar composition to that of the controls.

1. The fermentation of twenty-six different carbohydrates was studied in an artificial rumen.

2. The rates of fermentation varied widely, but except in the case of rhamnose the amount of methane produced was usually related to the amount of carbohydrate fermented (6.0 Cal/ 100 cal of substrate). There was also a correlation between the amount of carbohydrate fermented and the amounts of steam-volatile acids formed.

3. Glucose, fructose and sucrose were fermented rapidly but mannitol, sorbitol, glucuronic and galacturonic acids, glucosamine, D(–)-arabinose, ribose, sorbose, trehalose and starch were fermented very slowly or not at all. L(+)-Arabinose, xylose, galactose, mannose, cellobiose, maltose, lactose, raffinose, inulin, xylan and pectin were fermented at appreciable rates.

4. The methyl-pentose, rhamnose, was fermented but no methane was produced. Fucose was fermented very slowly.

5. The fermentation of sucrose and its constituent hexoses was characterized by a transient accumulation of lactate. The fermentation of rhamnose and of glucosamine was accompanied by permanent accumulation of lactate. No measurable amounts of lactate were produced when any of the other sugars were fermented.