PROGRESS IN EXPERIMENTAL PSYCHOLOGY 



This sympathetic system of ganglia and nerves, by- 

 the-bye, had long been a puzzle to the physiologists. Its 

 ganglia, the seeming centres of the system, usually mi- 

 nute in size, and never very large, are found everywhere 

 through the organism, but in particular are gathered 

 into a long double chain which lies within the body cav- 

 ity, outside the spinal column, and represents the sole 

 nervous system of the non-vertebrated organisms. Fi- 

 brils from these ganglia were seen to join the cranial 

 and spinal nerve fibrils, and to accompany them every- 

 where, but what special function they subserved was 

 long a mere matter of conjecture, and led to many ab- 

 surd speculations. Fact was not substituted for conject- 

 ure until about the year 1851, when the great French- 

 man Claude Bernard conclusively proved that at least 

 one chief function of the sympathetic fibrils is to cause 

 contraction of the walls of the arterioles of the system, 

 thus regulating the blood-supply of any given part. Ten 

 years earlier Henle had demonstrated the existence of 

 annular bands of muscle fibres in the arterioles, hitherto 

 a much mooted question, and several tentative explana- 

 tions of the action of these fibres had been made, par- 

 ticularly by the brothers Weber, by Stilling, who, as 

 early as 1840, had ventured to speak of "vaso-motor" 

 nerves, and by Schiff, who was hard upon the same 

 track at the time of Bernard's discovery. But a clear 

 light was not thrown on the subject until Bernard's ex- 

 periments were made in 1851. The experiments were 

 soon after confirmed and extended by Brown-Sequard, 

 Waller, Budge, and numerous others, and henceforth 

 physiologists felt that they understood how the blood- 

 supply of any given part is regulated by the nervous 

 system. 



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