37 



b. Non motile. 8. Escherichia pseudocoscoroba 



B. Sucrose not fermented Communis section of Durham. 



1. Dulcitol fermented with acid and gas. 



a. Salicin fermented with acid production. 



9. Escherichia cavicida 



b. Salicin fermented with acid and gas. 



(1) Motile. 10. Escherichia coli 



(2) Non motile. 



(a) Inosite not fermented. 



11. Escherichia coloidella 



(b) Inosite fermented with acid and gas. 



12. Escherichia coloides 



q. Salicin no change. 13. Escherichia metacoloides 



2. Dulcitol no change. 



a. Motile. 



(1) Maltose acid and gas. 



14. Escherichia paragrunthali 



(2) Maltose no change. 



15. Escherichia griinthali 



b. Non motile. 



(1) Maltose acid and gas. 



16. Escherichia colitropicalis 



(2) Maltose no change. 



17. Escherichia vesiculosus 

 II. Indol negative division (Smith). 18. Escherichia coli mutabilis 



The prominence given to the indol reaction and the fermentation of 

 dulcitol, adonitol, and maltose by Castellani and Chalmers is quite at var- 

 iance with the practices of American investigators. From the extensive 

 recent studies on carbohydrate and nitrogen metabolism it appears that 

 the acidi-lactici types are more closely affiliated with the strains in their 

 Genus Escherichia, than with the lactis-aerogenes forms and that the Genus 

 Cloaca of Castellani and Chalmers should be associated with the lactis- 

 aerogenes forms rather than with the proteus group. 



A very serious objection to such classifications as those of MacConkey, 

 Bergey and Deehan, and Jackson is their extreme flexibility and complexity; 

 for, as the number of fermentable substances or other characters observed 

 increases, the number of "varieties" increases geometrically (approaching 

 infinity) and soon produces a most unwieldy scheme. The number of 

 "varieties" is given by the formula 2 n where "n" is the number of char- 

 acters studied. Thus with eight characters there are 256 possible combi- 

 nations or "varieties." This number rises to 1,024 with 10 characters and 

 to 65,536 when 16 tests are considered. It is aparent therefore that to 

 regard each character as of similar and equal differential value will quick- 

 ly result in an unwieldy grouping. 



Another objection to these classifications is the arbitrary manner of 

 selecting the order in which reactions are to be employed for division. 

 Organisms which are very closely related may be far separated in two 



