594 PRACTICE OF PHYSIC. 



tenth, twelfth, fifteenth, sixteenth, eighteenth, and nineteenth, 

 there are but eighteen instances of termination, or one-ninth of 

 the whole. 



CXIII. As the terminations which happen on the seven days 

 last mentioned, are, upon the whole, few, and, upon any one 

 of them, fewer than those which happen on any of our supposed 

 critical days, so there are therefore nine days which may be 

 called Non-critical ; while, on the other hand, the many termi- 

 nations which happened on the seventh, fourteenth, and twen- 

 tieth days, afford a proof both of critical days in general, and that 

 these are the chief of them. Hereafter I shall mention an ana- 

 logy that renders the power of the other critical days sufficiently 

 probable. 



CXIV. It appears further, that as, of the terminations which 

 were final and salutary, not a tenth part happened on the non- 

 critical days, and of the terminations which were final and fa- 

 tal, though the greater number happened on the critical days, 

 yet above a-third of them happened on the non-critical, so it 

 would appear, that the tendency of the animal economy is to 

 observe the critical days, and that it is by the operation of some 

 violent and irregular cause that the course of things is sometimes 

 turned to the non-critical. 



CXV. What has been said gives sufficient ground for pre- 

 suming that it is the general tendency of the animal economy 

 to determine the periodical movements in fevers to be chiefly on 

 the critical days. At the same time, we must acknowledge it to 

 be a general tendency only, and that, in particular cases, many 

 circumstances may occur to disturb the regular course of it. 

 Thus, though the chief and more remarkable exacerbations in 

 continued fevers happen on the critical days, there are truly ex- 

 acerbations happening every day ; and these, from certain 

 causes, may become considerable and critical. Further, though 

 intermittent fevers are certainly very strongly determined to ob- 

 serve a tertian or quartan period, we know there are circum- 

 stances which prevent them from observing these periods exactly, 

 and which render them either anticipating or postponing so 

 much, that the days of the paroxysms come to be quite changed ; 



