Exceptions to the Law of Heredity. 205 



which appear to bring under the law of heredity the most refrac- 

 tory cases, the most formidable exceptions. By penetrating farther 

 into the vital and mental dynamism of man, we shall probably 

 have a glimpse of that mysterious elaboration whereby unity 

 produces diversity, and causes give rise to effects very dissimilar 

 to themselves. We shall then see how heredity seems to disap- 

 pear, when it cannot be grasped. 



IV. 



If we take up any engine of simple structure, such as a win- 

 nowing machine, a plough, or a scarifier, and some slight injury 

 befalls it, it is probable that it will not be less serviceable : a 

 trifling cause produces only trifling effects; effect and cause are 

 mutually equivalent, and there is in their relation nothing sur- 

 prising. But if the one in question is a complicated engine, such 

 as a locomotive, or a factory engine, the case is very different ; 

 here an insignificant cause may produce terrible effects : the engine 

 may run off the rails, an explosion or a fire may take place. 

 Between causes and effects there is a disproportion which experi- 

 ence alone reveals. If now we consider, instead of a mechanism 

 constructed by the hand of man, those natural mechanisms called 

 organisms, where wheelwork and arrangement extend to even the 

 minutest details, then the disproportion between effects and causes 

 will become enormous ; a drop of prussic acid or the puncture 

 of a carbuncle will throw the machine out of order in a few 

 hours. Finally, in that mental mechanism which is still more 

 complicated, and where the impulses, tendencies, forces, conscious 

 and unconscious processes, do but attain that momentary equili- 

 brium which we call the actual state of consciousness the dispro- 

 portion between causes and effects transcends all assignable limits. 

 A rush of a little alcoholized blood to the brain, the fumes of 

 opium or hasheesh may produce the most surprising results in the 

 mental machine. A few drops of belladonna or of henbane give 

 rise to fearful visions. A little pus accumulated in the brain, a 



