106 MEXTAL EVOLUTION IN ANIMALS. 



destructive agencies; the Massive Pains, as a class, from 

 excessive function or insufficient nutriment :" also that 

 " Massive Pains, when pushed to an extreme, merge into the 

 Acute Class," so that " the two classes are rather indefinite in 

 their limits, being simply a convenient working distinction, 

 not a natural division." Hence it follows that Pains of both 

 classes " are the subjective concomitants of an actual disrup- 

 tion or disruptive tendency in some one (or more) of the 

 bodily tissues, provided the tissue be supplied with afferent 

 cerebro-spinal nerves in unbroken connexion with the brain." 

 Eeferring the reader to Mr. Allen's own essay for all matters 

 of detail and criticism, I shall merely say that in my opinion 

 he has successfully established this formula as applicable to 

 all cases of Pain. His view concerning the physiology of 

 Pleasure is substantially the same as that of Mr. Spencer 

 already quoted ; but it is somewhat more extended and pre- 

 cise. This view is that Pleasure is " the concomitant of a 

 normal amount of activity in any portion or the whole of the 

 oi'ganism," supplemented with the important addendum that 

 " the strongest Pleasures result from the stimulation of the 

 largest nervous organs, where activities are most intermittent ;" 

 so that the amount of Pleasure is "in the direct ratio of the 

 number of nerve-fibres involved, and in the inverse ratio of 

 the natural frequency of excitation." Hence " we see wdierein 

 the feeling of Pleasure fails to be exactly antithetical to the 

 feeling of Pain, just as their objective antecedents similarly 

 fail. Massive Pleasure can seldom or never attain the inten- 

 sity of Massive Pain, because the organism can be brought 

 down to almost any point of innutrition or exhaustion ; but 

 its efficient working cannot be raised very high above the 

 average. Similarly any special organ or plexus of nerves can 

 undergo any amount of violent disruption or wasting away, 

 giving rise to extremely Acute Pains ; but organs are very 

 seldom so highly nurtured and so long deprived of their 

 appropriate stimulant as to give rise to very Acute Pleasure." 

 Now towards what conclusion do these generalizations 

 point ? They clearly point to the conclusion, which I do not 

 think is open to any one valid exception, that Pains are the 

 subjective concomitants of such organic changes as are harm- 

 ful to the organism, while Pleasures are the subjective con- 

 comitants of such organic changes as are beneficial to the 

 organism — or, we must add, to the species. The more this 



