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The serum opacity reaction of Streptococcus pyoyenes (Ward & Rudd, 1938) has been found to be associated with a lipoproteinase which acts upon the ocl lipoprotein of the serum of various species to produce opa.lescence (Krumwiede, 1954; Rowen & Martin, 1963). Some observations on the general properties of the streptococcal factor and on the nature of the reaction in aged serum are recorded in an accompanying paper (Hill & Wannamaker, 1968). Although the nature of the reaction is not fully defined and other factors may possibly produce opalescence in serum, the terms serum opacity reaction (SOR) and lipoproteinase will be used interchangeably in this communication. Data presented by Ward & Rudd (1938), Gooder (1961), and Kohler (1963) suggested to us that production of the serum opacity reaction was rather closely associated with serotype a.s determined by M and T antigens. Burthermore, both Gooder and Kohler concluded that strains which were difficult to type by the Mprecipitin method generally produced a, SOR but that M-typable strains rarely produced this reaction. If an inverse relationship between M-antigen and SOR could be substantiated, the serum opacity reaction might be useful as a preliminary test to characterize group A strains as M-positive or M-negative. Further investigation of the production of this enzyme in individuaWl strains in relationship both to serotype and to production of an M-antigen and an investigation of the consistency of production of lipoproteinase by individual strains were therefore undertaken.

Copyright © Cambridge University Press 1946, In Portugal endemic pellagra has been known for many years. Since 1896 about twenty-five papers have dealt with the subject, the most valuable being those of Pereira da Silva (1905) and Manuel Ferreira (1927). No country-wide statistics of the prevalence are available, but all authors agree that pellagra is widespread in all the maize-growing districts of Portugal. The purpose of the present work was to study the disease, using some of the recent methods for the appraisal of nutritional status.

The paper includes a description of studies on Anopheles gambiae Giles in the insecticide-free Umbugwe area of Tanganyika, and the results of dissections of A. gambiae and A. funestus Giles for sporozoite infections.The densities of A. gambiae and A. funestus were assessed in houses by pyrethrum spray catches in 90 houses distributed in ten villages in the Umbugwe area between March 1960 and February 1962. A. gambiae was seasonally abundant, a sharp increase in density being associated with periods of rain. A. funestus type form was scarce in houses throughout the year, although a larval survey showed it to be the most common member of the complex of A. funestus in the area.The average ratio of fed to gravid individuals of A. gambiae was 2·3:1 from June 1960 to November 1961, with peaks reaching 7:1 in March 1960 and 7·5:1 in January 1962. The peaks were attributed to rapid increase in production of adults during the limited period of the rainy seasons that followed very dry conditions.Thirteen per cent, of recently fed individuals of A. gambiae were found in the exit window traps of experimental huts, having attempted to leave the huts on the night of feeding.Two distinct types of huts are commonly found in the area, the tembe, which is large, divided into an average of five rooms by walls that are usually incomplete at the top, and accommodates large numbers of cattle as well as humans; and the banda, which is smaller, divided only into two rooms and seldom housing any domestic animals. Precipitin tests showed that whereas only 20 per cent, of individuals of A. gambiae taken in tembe had fed on man, in banda huts the percentage was 77. It was also shown that there was a dispersal of A. gambiae within a hut shortly after feeding. In a tembe. one-third of the individuals positive for man, and one-quarter of those positive for cattle had moved to rooms other than those in which they had fed.A sporozoite rate of 1·47 per cent, was found among 3,746 specimens of A. gambiae dissected. Of the total number of 55 sporozoite-positive females of A. gambiae, 39 were found among the 424 individuals dissected in February 1962, thereby indicating unusually heavy transmission during the early part of 1962. A. funestus type form appeared to be of virtually no importance in malaria transmission in the Umbugwe area. Transmission by A. gambiae was highly seasonal, for although the percentage of gland-positive specimens was slightly higher in the long dry season than in the rainy season, the much larger mosquito population in the latter led to a higher number of infective bites in the rainy seasons. The highly seasonal transmission by A. gambiae was reflected in the results of examination of blood-films of people attending the Government dispensary.

and of resistance, either natural or acquired, possessed by an individual or a group of animals. The method of titration of foot-and-mouth disease virus (FMDV) in cattle by inoculation of the tongue (Henderson, 1949) has formed the basis for many of the standard procedures used in FMDV research involving cattle. Comparatively little work, however, has been recorded on the development of suitable methods of titration of FMDV in pigs. Brooksby (1950) inoculated individual animals with single dilutions of virus intradermally in the tongue and snout in his studies of virus strains showing natural adaptation to swine. GraJves & CunliSe (1960) carried out some comparative work on the sensitivity of pigs to different routes of inoculation and concluded that the inoculation of the coronary band region of the foot was the most sensitive £or the detection of virus. They developed a titration scheme using the simultaneous inoculation of several dilutions of virus into individual animals and showed that their results were reproducible within good statistical limits. Lucam, Dhennin, Dhennin & Fedida (1962) subsequently compared titration end-points using coronary-band and snout inoculation and confirmed the high sensitivity of the coronary-band region. Burrows (Communication to the Research Group of the Standing Technical Committee of the European Commission for the Control of Foot-and-Mouth-Disease, June 1963, summarized in F.A.O. document 15766/E) reported that the bulb of the heel of the foot was a convenient and highly sensitive site of inoculation for titration, innocuity testing and challenge of immunity procedures. Some details of the use of this method for these purposes have been recorded (Girard et al. 1963; Burrows, 1964a, b). It is desirable, when proposing an a.ssay method, to attempt to determine the precision of the method and also to compare the results with those given by established titration procedures. This paper presents the results of a number of comparative titrations of some FMDV strains in cattle, mice and pigs, with particular reference to the results obtained in pigs by the bulb of the heel inoculation method.