Rickets in Rats. 



193 



strain S, is specific as is the original filtrate. But with the second, 

 obtained from the resistant strain R, Doctor Wollstein of the Rocke- 

 feller Institute has found a marked action on Shiga, on Flexner 

 and on Hiss dysentery bacilli. In consequence of this observa- 

 tion, we have been able, by a method of successive passages 

 through appropriate strains, to extend the lytic power to other 

 species, as typhoid and paratyphoid bacilli, and have obtained by 

 this somewhat different technique results similar to those recently 

 published by Bordet and Ciuca. 1 



4. We have observed also that the modified coli of Bordet and 

 Ciuca, e.g., the coli which has resisted the lytic action, contains 

 two types of organisms: a mucoid and fluorescent type, coli M 1, 

 and a non-mucoid and translucent type, coli M 2. Both types, 

 once isolated, keep their individuality after many passages in 

 artificial media, but if the non-mucoid coli M 2 is submitted again 

 to the lytic agent, we find amongst the organisms which resist a 

 certain number of mucoid bacilli. 



97 (1679) 



A dietetic production of rickets in rats and its prevention by an 



inorganic salt. 



By H. C. SHERMAN and A. M. PAPPENHEIMER. 



[From the Departments of Chemistry and Pathology, Columbia Uni- 

 versity, New York.] 



The occurrence of rickets in white rats maintained under 

 laboratory conditions has been well known to pathologists since 

 the first publication of Morpurgo in 1900; and the essential 

 identity of the lesions with those of human rickets has been 

 established by the work of Morpurgo himself, of Schmorl, of 

 Weichselbaum, and especially by the detailed histological studies 

 of Erdheim. One of us (A. M. P.) also has had opportunity to 

 become familiar with the disease in rats, in the course of an 

 investigation of the possible influence of the thymus upon the 

 teeth and skeletal system. In none of these investigations, how- 

 ever, were the dietary conditions of the rats standardized and 

 controlled. 



1 C. R. Soc. beige Biol., T. 1921, lxxxiv, 278. 



