130 SUPPOSED INSTANCES [oh. ix 



fostered the growth of the first organism almost to the 

 exclusion of the second, and at another time fostered the 

 growth of the second almost to the exclusion of the first. 



If, after each appearance of 8. /aecaiis, the strain had 

 been guaranteed pure by the method of successive plating 

 and growth from a single organism, the results obtained 

 would have had more weight. 



It is worth noting that the strains of B. /aecaiis al- 

 caligenes used in all these experiments, and supposed to 

 have been derived from B. typhosus in the first place, showed 

 no tendency to revert to B. typhosus. It is also interesting 

 to compare these experiments with those of Adami, Abbott and 

 Nicholson (1899) who obtained from B. coli grown in peri- 

 toneal fluid cocci which did not ferment sugars or form indol, 

 and yielded colonies which were white and opaque and 

 resembled those of a streptococcus. After 3 passages through 

 the guineapig these cocci yield short bacilli which however 

 were still unable to ferment sugars. They state that B. 

 typhosus was modified in much the same way under similar 

 conditions. 



Qi) The cha/ngefrom B. typhosus to B. faecalis alcaligenes 

 after growth in, the diluted a/nd filtered urine of a typhoid 

 carrier. 



(Page 239, exp. III.) This experiment was practically a 

 repetition of the last, the same strain of B. typhosus being 

 used (laboratory stock "R") but the urine was that of a 

 different typhoid carrier "I". The result was the same, 

 colonies of typical B. typhosus being found at first but after 

 a month's interval colonies of a non-fermenting and non- 

 agglutinating coliform organism being alone found. To this 

 experiment the same criticism applies. 19 other experiments 

 were made but with negative results. 



Summary. The evidence that Major Horrocks brings 

 forward in support of the claim that in the course of his 

 experiments transmutation occurred is inconclusive. He is 

 unable in any case to guarantee as pure the culture with 

 which he was dealing. He is unable to exclude definitely, in 

 some of his experiments, the occurrence of a secondary 



