92 C. F. ROBINOW 



Table II 

 Comparison of spore and crystal size with spore DNA 



Organism DNA-P/Spore Spore Volume Crystal Volume 



(10-i6g.) iix^xlO^) iji^xK^) 



It was also evident here from studies of average crystal size (Fig. 5) and 

 average crystal volume (Table II) that those varieties with the smallest 

 spores and least amount of DNA also produced the smallest crystals. This 

 relationship suggests a possible origin for the crystal protein. 



References 



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 Fitz-James, P. C. 1955. The phosphorus fractions of B. cereus and B. mega- 



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 Hannay, C. L. 1953. Crystalline inclusion in aerobic spore-forming bacteria. 



Nature 172: 1004. 

 Hannay, C. L. and P. C. Fitz-James. 1955. The protein crystals of Bacillus 



thuringiensis Berliner. Canad. J. Microbiol. 1 : 694-710. 

 Howie, J. W. and J. Cruickshank. 1940. Bacterial spores as antigens. J. 



Path. Bact. 2: 235-242. 

 Schmidt, G. and S. J. Thannhauser. 1945. A method for the determination 



of desoxyribonucleic acid, ribonucleic acid and phosphoproteins in ani- 

 mal tissues. J. Biol. Chem. 161: 83-89. 

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Chem. 161: 293-303. 

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Informal Discussion 



SussMAN: I would like to address my question to either Dr. Robinow or 

 Dr. Fitz-James. Have the cytological stages in the development of the spores 

 been tested with DNA-ase, or by extraction with hot perchloric acid, in 

 order to determine whether the material that stains Feulgen-positive is really 

 DNA? 



Fitz-James : Every state except the transient basophilic stage. Shortly after 



