1. Group A streptococci sometimes produce in broth culture an extracellular proteolytic enzyme. 2. Under suitable cultural conditions the enzyme has been demonstrated in representative cultures of most of the Griffith types. Its production by a given strain may be suppressed by serial passage through mice and the variant so produced has been found to maintain this change in character on subculture in artificial media. 3. Under certain conditions, the enzyme attacks the type-specific M antigens of all the group A streptococci so far tested, with the exception of that of type 28. The enzyme exhibits its maximal activity at 37°C.: Extracts made from enzyme-producing cultures which have been grown at this temperature lack the M antigen; enzyme-producing strains may sometimes be induced to yield M substance in extracts by culturing the streptococci at 22° C. Cultures which, when grown at 37° C. yield M substance in extracts, do not produce the enzyme. 4. Human and rabbit fibrin are attacked and streptococcal fibrinolysin is also inactivated by the enzyme. Other susceptible substrates include casein, milk, gelatin, and benzoyl-l-arginineamide but not l-leucylglycylglycine. 5. The general properties of the enzyme resemble those of papain and some of the cathepsins: It is active under the reducing conditions produced in broth cultures by the presence of living bacteria; it is also activated by substances which reduce disulfide to sulfhydryl groups, e.g. potassium cyanide, cysteine, glutathione, and thioglycollic acid, but it is not activated by ascorbic acid. The enzyme is inactivated by iodoacetic acid and also by normal rabbit or mouse serum.

SUMMARYThe ' intracellular' teichoic acids from two strains of group D streptococci (strains 8191, 39) were purified and their serological and chemical properties examined. Both compounds reacted serologically with group D streptococcal antiserum. Chemical analysis showed them to be polymers of glycerol phosphate containing a high proportion of glucose and bearing alanine ester residues on the sugar; it is likely that the glucose comprises di-and tri-saccharide residues attached to most or all of the glycerol units.Analysis of group antigen preparations from three other strains of group D streptococci previously studied indicated that they are serologically identical with and chemically similar to the teichoic acid from strain 39. The difference in serological activity between the intracellular teichoic acid from strain 8191 and that from the other four strains is probably associated with small differences in chemical composition, particularly with respect to glucose content.

Bees feed almost exclusively on nectar and pollen from flowers. However, little is known about how food availability limits bee populations, especially in high elevation areas. Foraging distances and relationships between forager densities and resource availability can provide insights into the potential for food limitation in mobile consumer populations. For example, if floral resources are limited, bee consumers should fly farther to forage, and they should be more abundant in areas with more flowers. I estimated subalpine bumble bee foraging distances by calculating forager recapture probabilities at increasing distances from eight marking locations. I measured forager and flower densities over the flowering season in six half-hectare plots. Because subalpine bumble bees have little time to build their colonies, they may forage over short distances and forager density may not be constrained by flower density. However, late in the season, when floral resources dwindle, foraging distances may increase, and there may be stronger relationships between forager and flower densities. Throughout the flowering season, marked bees were primarily found within 100 m (and never >1,000 m) from their original marking location, suggesting that they typically did not fly far to forage. Although the density of early season foraging queens increased with early-season flower density, the density of mid- and late-season workers and males did not vary with flower density. Short foraging distances and no relationships between mid- and late-season forager and flower densities suggest that high elevation bumble bees may have ample floral resources for colony growth reproduction.