Two histochemical sequential staining techniques, Alcian blue-PAS (AB-PAS) and high-iron-diamine-Alcian blue (HID-AB), which differentiate neutral from sulfated and non-sulfated acid mucosubstances, were applied to sections from the gastrointestinal tract of eleven mammalian species, including man, to study patterns of distribution of gastrointestinal epithelial mucosubstances. The application of these techniques under uniform laboratory conditions enabled a detailed description of epithelial mucosubstances throughout the gastrointestinal tract relative to location in each species as well as a comparison of their distribution among various species. The results showed that all of the 11 species studied had a distinctly different distribution of epithelial mucosubstances throughout the entire gastrointestinal tract. These differences were most obvious in the stomach and duodenum. In each species, neutral mucosubstances were most evident in the stomach and acid mucosubstances in the intestines, with sulfomucins most prominent in the large bowel. Acid mucosubstances were noted in Paneth cell granules of rodent species only. These histochemical observations make available a uniform comparative basis for the normal distribution of mammalian gastrointestinal mucosubstances which should facilitate their study in diverse pathological conditions.

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SYNOPSIS. Cryptosporidium wrairi sp. n. is described from the laboratory guinea pig Cavia porcellus. The life cycle is given insofar as it is known. Two schizogonous generations are described; the 1st with 8 merozoites, the 2nd with 4 merozoites. The latter generation was previously referred to as the sporulated oocyst, but evidence is presented to show that it is a schizont. Micro‐ and macrogametogony are also described. No oocysts were found. Cross‐transmission to mice, chickens, turkeys and rabbits was unsuccessful. The generic character of oocysts with 4 naked sporozoites is discarded and the presence of endogenous stages in the striated border of epithelial cells is used as the emended generic character. A listing of valid and non‐valid species is given.

Globule leucocytes (GL) first noted by Weill ('19) in the intestinal tract of certain mammals, have been described, since, in many species. The classification and function of these cells, however, is still under discussion. We have studied GL in the cat using histochemistry at light and electron microscopic levels. In this species, GL are concentrated in the intestinal mucosa; they are found less frequently in the gallbladder and only rarely in other organs. GL are usually located between the epithelial cells of the gut, seldom in the underlying lamina propria. They appear to be migratory cells of mesenchymal origin, representing an independent cell population. GL are characterized by large eosinophilic globules in their cytoplasm. The globules contain strongly basic proteins associated with phospholipids and neutral mucosubstances which, in the colon, are encased in a capsule of sulfated mucosubstances. A t the ultrastructural level the typical globules consist of a dense, homogeneous matrix enclosed by a single membrane; they show, however, great variation in their morphologic appearance, reflecting, possibly, different stages in the process of accretion and utilization of their content.

The topographical distribution of alkaline phosphatase, acid phosphatase, and reduced diphosphopynidine nucleotide (DPNH) diaphorase in the small intestine of the normal rat, ENZYMES OF THE SMALL INTESTINE