CHAP. IX.] METHODS OF ABBREVIATION. 149 



1st. If the property B be present in one of the productions, either 

 the properties A, C 9 and D, are all absent, or some one alone of them 

 is absent. And conversely, if they are all absent it may be con- 

 cluded that the property A is present (7). 



2nd. If A and C are both present or both absent, D will be ab- 

 sent, quite independently of the presence or absence ofB (8) and (9). 



I have not attempted to verify these conclusions. 



