Further observations onBacillus thuringiensisBerliner and other sporeforming bacteria

does not appear. First page follows. Introduction In 1951 our laboratory reported (Steinhaus, 1951) on some aspects of the biological control potentialities of certain sporeforming bacteria, together with some general considerations of Bacillus thuringiensis Berliner as an insect pathogen and as a possible agent to use in the control of the alfalfa caterpillar. This was followed with similar studies by the senior author’s students (Tanada, 1953); (Hall, 1954); (Clark, 1954) and an associate (Thompson, 1954). In the meantime, we have been making incidental observations on B. thuringiensis and its pathogenicity for several species of insects being reared in the laboratory. Although in their studies on B. thuringiensis, (Berliner (1915)) and (Mattes (1927)) noticed that the vegetative remains of the sporulating cells assumed a rhomboid shape, the description by Hannay, in 1953, of “crystalline inclusions” in the sporangium of the organism made room for further interpretations of the data being accumulated on this bacillus. Neither Berliner nor Mattes attributed to these bodies any role in the disease process caused by the ingestion of sporulating B. thuringiensis. Hannay, on the other hand, speculated that the inclusions were connected with the pathogenicity of the bacillus. Heretofore our own investigations had never included cytological studies of the bacillus at the stage the inclusions are formed. In retrospect, however, it would appear that these bodies were present in some of our preparations, as evidenced by figures 2 and 3 in our 1951 paper (Steinhaus, 1951). With the staining methods used, however, the free inclusions were not recognized as anything other than part of the “remains of the vegetative cells.”