494 abstracts: bacteriology 



wrinkled. This is the case in the boxes used for shipping the dates from 

 the Sahara to Marseilles. 



The Deglet Noor may ripen on the tree in many of the Saharan cases 

 but this cannot take place in the southwestern United States because of 

 the extreme dryness in the deserts. 



A good system of slow artificial ripening for Deglet Noor dates may 

 become important in Algerian and Tunisian commerce. Further experi- 

 ments are necessary, however, for securing conditions of humidity and 

 terrfperature best suited to this method. 



Maude Kellerman. 



BACTERIOLOGY. — The virulence of Bacillus pestis of ground-squirrel 



origin. George W. McCoy and Charles W. Chapin. Public 



Health Bulletin No. 53, U. S. Public Health Service, 1912. 



At the Federal Laboratory at San Francisco, there have been isolated 



during a period of three years, a large number of cultures of the plague 



bacillus from naturally infected ground-squirrel (Citellus beecheyi, 



Richardson). The virulence of 68 cultures was tested, wild rats being 



used as the test animals. One of the cultures indistinguishable from 



any of the others was found to be avirulent. The others were fatal to 



the test animals. The avirulent culture immunized against a virulent 



culture of the plague bacillus. G. W. M. 



BACTERIOLOGY.- — A note on the susceptibility of ground-squirrels 



(Citellus beecheyi, Richardson) to tuberculosis. George W. McCoy 



and Charles W. Chapin. Public Health Bulletin No. 53, U. S. 



Public Health Service, 1912. 



This paper supplements a previous one in which the presence in nature 



of tuberculosis among ground-squirrels was reported. The organism 



was shown to agree with the bovine type of B. tuberculosis. 



The present paper reports the results of artificial infection of ground- 

 squirrels. The results indicate that they are uniformly susceptible to 

 the disease, death occurring in from 46 to 98 days. G. W. M. 



BACTERIOLOGY. — Immunity of wild rats (Mus norvegicus) to plague 



infection. George W. McCoy and Charles W. Chapin. Public 



Health Bulletin No. 53, U. S. Public Health Service, 1912. 



Observations made in San Francisco three years prior to the present 



experiments showed that there was a considerable degree of immunity 



to plague infection among the wild rats. Another series of experiments 



