The possibility of using fluorescence-microscopy as a routine method for the examination of large numbers of specimens for M. tuberculosis and M. leprae was investigated. Fluorescence-microscopy yields a slightly higher proportion of positive results than the routine Ziehl-Neelsen technique, the examination-time is considerably reduced, the method appeared ultimately to cause less eye-strain and it is cleaner and easier than the Ziehl-Neelsen method. These advantages outweigh the disadvantages of cost of equipment and training and maintenance of a suitable team of workers. The danger of obtaining false-positive results can be overcome by experience and checking of scanty positive and doubtful smears by the Z.N. technique. The method is at present used for about 50% of sputa received for examination. Examination of leprosy smears by F.M., although it appears to give equally good results as the Z.N. technique, has been abandoned, mainly because routine smears submitted for this examination are often unsuitable for this method and have to be restained and re-examined by Z.N. to reach a diagnosis of reasonable certainty.
Serum calcium values have been determined in groups of Bantu children and adults in good outward health. It has been found that, in common with other populations dwelling in tropical and semitropical countries, low serum calcium values are frequently observed. Discussion of our results and other relevant information indicates the following: (1) Low serum calcium values are compatible with good outward health. (2) The values probably reflect habituation to a relatively low intake of calcium. (3) They do not provide an indication of the extent of stores of body calcium. (4) They do not predispose to (a) low concentration of calcium in the breast milk; (b) poor mineralization of bone; (c) proneness to fracture bones, or (d) an increased incidence of dental caries.