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A comparative analysis of the fine structure of the microvilli on jejunal and colonic epithelial cells of the mouse intestine has been made. The microvilli in these two locations demonstrate a remarkably similar fine structure with respect to the thickness of the plasma membrane, the extent of the filament-free zone, and the characteristics of the microfilaments situated within the microvillous core. Some of the core microfilaments appear to continue across the plasma membrane limiting the tip of the microvillus. The main difference between the microvilli of small intestine and colon is in the extent and organization of the surface coat. In the small intestine, in addition to the commonly observed thin surface "fuzz," occasional areas of the jejunal villus show a more conspicuous surface coat covering the tips of the microvilli. Evidence has been put forward which indicates that the surface coat is an integral part of the epithelial cells. In contrast to the jejunal epithelium, the colonic epithelium is endowed with a thicker surface coat. Variations in the organization of the surface coat at different levels of the colonic crypts have also been noted. The functional significance of these variations in the surface coat is discussed.

Studies of gastric acid secretion and mucosal appearances have been made in a group of 14 patients suffering from hypopituitarism. Achlorhydria was found in six of the patients suffering from Addison's disease but in only one patient suffering from hypopituitarism. In both groups the mean gastric secretion of hydrochloric acid was considerably lower than in a group of control subjects and replacement therapy with cortisone and DOCA in Addison's disease and cortisone and thyroid extract in hypopituitarism failed to restore gastric function to normal. A constant correlation was not found between gastric acid secretion and mucosal appearances.

The Valley of Oaxaca's large flat floor, high water table, low erosion rate, and frost-free floodplain give it a higher agricultural potential than that of most surrounding areas. The development of the pot-irrigation system early in the Formative period gave it a head start over other valleys, where the low water table did not permit such farming; Oaxaca maintained its advantage by assimilating canal irrigation, barbecho, infield-outfield systems, flood-water farming, and hillside terracing as these methods arose. With the expansion of population in the high-water-table zone of the high alluvium, competition for highly productive land and manipulation of surpluses may have led to initial disparities in wealth and status; competition probably increased when canal-irrigation systems were added during the Middle Formative, improving some localities to the point where one residental group owned land more valuable than that of its neighbors.

1. Typical pneumococci were present dunng the winter months in the throat secretions of a large percentage of healthy individuals in city and country. 2. A higher percentage of atypical strains of pneumococci have been obtained from healthy persons than from those suffering from pneumonia. In the latter cases the atypical strains may have been overlooked, because of the larger number of typical pneumococci present. Many of the atypical strains seem to be closely related to the streptococci. 3. The so-called Streptococcus mucosus Schottmuller, which has hitherto been classed with the distinct streptococci, is placed as a definite variety among the pneumococci, and it is recommended that the name be changed to Streptococcus lanceolatus, var. mucosus. 4. A lower percentage of strains of pneumococci virulent for rabbits in the doses used has been obtained from normal cases by rabbit inoculations of mass cultures than from cases of pneumonia by the same method. 5. Since the virulence of pneumococci may be rapidly increased for a susceptible species of experimental animal by successive passage, and since pneumococci obtained from most pneumonias are more virulent for experimental animals than are those obtained from healthy individuals, therefore the virulence of pneumococci from cases of human infection is probably increased for human beings; hence cases of pneumonia should be considered to a certain degree as contagious and, since the virulence of the pneumococcus may be quickly increased and since the organism is very prevalent in normal sputum, all possible measures should be taken to restrict public expectoration. 6. By repeated inoculations into sheep of a pneumococcus strain, a specific protective power of this serum for mice is developed against the homologous strain and against certain other strains, one morphological variety (Streptococcus lanceolatus, var.mucosus) being thus clearly differentiated from other strains. 7. Coincident with this production of protective power, a slight specific increase of the sheep serum in phagocytic power in vitro has been observed with some strains of pneumococci, all strains of Streptococcus lanceolatus, var. mucosus, acting similarly with the serum produced by the inoculation of one strain; the strains of some other varieties, however, have shown no definite relationship between the phagocytic power and the protective power of the serum.