THE NERVOUS SYSTEM. 445 



not prevent the secretion of urine by dividing all the nerves of the 

 kidney, he divided the renal artery, and passed a canula between 

 the two portions, so that no nerves could run to the organ along 

 the arterial coats. Secretion ceased. But the functions of the 

 small vessels were unlikely to continue when the trunk was so 

 severely injured : just as we shall find the functions of the ovaria 

 or of the testis often to be arrested by dividing the Fallopian 

 tube or vas deferens. For what purpose of nutrition or supply 

 of properties can a ganglion be particularly required just in the 

 situation of the ophthalmic or the otic ? But, if we reflect that 

 the motions of the iris and muscles of the internal ear must 

 be regulated by the condition of certain other parts, we can under- 

 stand why those ganglia exist in their respective places. For the 

 ganglionic system, no doubt, communicates important influences. 

 The functions of each of the complicated and numerous organs of 

 all but the lowest animals, require constantly to vary according 

 to the condition of others. Not only, for instance, does every 

 organ of digestion, assimilation, and excretion, require to be in 

 nice adjustment with another and with all, but is each affected by 

 organs not forming a part of the group nor necessary to their 

 powers. The nutritive functions do not require the brain ; yet 

 if the brain is harassed by a disagreeable state of feeling 

 sorrow, vexation, anxiety, &c. whatever be its intensity, that 

 group suffers, and dyspepsia, diarrhoea or costiveness, pale or 

 morbidly coloured stools, a morbid colour of the urine and the skin, 

 in some degree or other result. Whereas, in a happier state of 

 mind, the functions, caeteris paribus, go on well ; and, in a truly 

 happy state, persons are often struck with the excellence of their 

 condition. The converse operation of all these upon the brain is 

 as certain* Now, if such is the mutual influence of organs not 

 necessary, except indirectly, to each other, but bound up, where 

 they all exist, into a common whole, so that the well-being of each 

 is essential to the well-being of the whole, we may well conceive 

 the important influence of organs upon each other which co- 

 operate in function. I conceive the influence of organs upon each 

 other to be incessant, and to be ever varying accordingly as the 

 state of each influencing organ varies : and that they are all at 

 all times influenced and influencing. This constant mutual in- 

 fluence is indispensable to perfect function, though it frequently 

 disturbs function : and, as all seem thus bound together into a 

 common whole, the removal of this general and particular influ- 



