'Proteins, vitamins, and minerals play an important role in the reproductive cycle. Some experiments by Dagg's [sic] [note: 'Daggs, C.G., Jour. Nutrition, 4:443.'] employing four proteins, muscle meat, liver, egg and kidney, and used in connection with diets otherwise inadequate, proves the influence of protein on the reproductive cycle in dogs. The number of young born. their growth, maternal nitrogen balance, as well as blood and urine analysis and volume and analysis of the milk, were studied. No young were born on the kidney diet. It appears that a more favourable nitrogen balance was obtained on the liver diet than on either the egg or muscle meat diets. Liver, likewise, favoured a higher quantity of milk with a greater fat content than either of the other proteins studied. Pups suckling the liver fed dogs grew faster than on the other protein diets. The nutritive importance of manganese has recently [326-327] come in for study in both plants and animals.It has been found that diets otherwise adequate but lacking in this element were productive to testicular degeneration in the males. In the females the estrus cycle was not interfered with, but htere was a deficient lactation. In the studies of the writer degeneration of the testes has been observed in several instances.' (326-327)