Percy R. Howe

Low Calcium Rickets in the Guinea Pig.

Summary Typical rachitic changes in bones and teeth have been produced in young guinea pigs by a diet low in calcium and in vitamin D. In older animals the changes in the bones were obscured by arrested skeletal growth, but those in the teeth were constant.

The effect of the scorbutic state upon the production and maintenance of intercellular substances.

Summary and Conclusions The scorbutic state may be characterized as one affecting supporting tissues in which the cells are unable to produce and maintain intercellular substances. This condition affects various supporting substances to a different degree, and is most marked in those in which the intercellular substance is calcified, as the dentine of teeth and the matrix of bone. The characterization applies to cartilage and connective tissue, and, by inference, to other intercellular substances, including that of blood vessels. The hypothesis is entertained, based upon the study of repair in in-cisor teeth of scorbutic guinea pigs, that in the formation of intercellular substances there is a change of the material from a liquid to a sollid or jell state, and that the missing factor in the scorbutic condition is one affecting the jelling or setting of a liquid product.

The epithelial tissues in experimental Xerophthalmia.

Conclusions Deprivation of the anti-xerophthalmic vitamine (fat soluble A) affects specifically epithelial tissues. This effect is manifested in cells having presumably widely different chemical (secretory) functions, and terminates in the complete loss of specific function and the transformation into a common type of chemically inactive (noln-secretory) epithelium.