CHAPTER XX. 



Some Further Applications of the Symbolical Method. 



It has been observed that a particular mal-euvironment may 

 extend over many years : it may, in fact, date from the very 

 first moments of life. Now it is obvious that, if the E has been 

 in operation during a long time, rendering the individual from 

 day to day more and more prone to the disease, a gradual 

 change in S must have been taking place all this time ; a specific 

 u deficiency " may thus go on increasing, until finally the disease 

 is capable of being set up by a numerically small E, and thus, at 

 the time of the actual occurrence, the causation might be repre- 

 sented by such a formula as the following : S 9 -r-E 2 = 1 1. 



In the foregoing table, however, the S is supposed to represent 

 that part of the individual which is the pure and simple outcome 

 of heredity as distinguished from those structural peculiarities 

 which have been wrought through E, while E symbolizes the 

 entire specific mal-environment from the period of birth. It 

 would be more accurate to start from the earliest period of 

 uterine life, for we have seen that the intra-uterine E plays a 

 very important part in shaping the destiny of the individual,, 

 but it is sufficient for our purpose to take the period of birth as 

 our starting-point. At this time the tendency to a particular 

 disease might be S, ; during a number of years' exposure to< 

 a specific mal-E this might change to S ]0 . In such a case the 

 causation would be best symbolized : S 1+9 + Ej= 1 1. 



If we wish to ascertain the entire share which E has taken 

 in causation, it is in fact necessary, in the case of very many 

 diseases, to extend our survey over the whole previous life. 

 Thus, in discussing the causation of insanity, Maudsley says : 

 u What should ever be borne in mind is, that all the conditions''' 

 (italics are mine: by "all the conditions" the author is here 

 referring to conditions of structure as well as of E) " which 



