372 D. OGATA AND SWALE VINCENT 



As is clear from the tables, almost every stimulation in this 

 series, produced a reflex fall of blood-pressure, and no signifi- 

 cant qualitative difference is observable either with different 

 modes of stimulation or with different methods of anaesthesia 

 or with different portions of the skin. 



That this statement is applicable almost without any modifi- 

 cation to the results of stimulation of muscles and intestine 

 will immediately be understood from the tables on page 373. 



Thus it is fairly clear that the stimulation of nerve terminals 

 in the skin, muscles, and the intestine produces usually a reflex 

 fall of blood-pressure, as was reported by Vincent and Cameron. 



But the threshold of stimulation for the nerve-terminals in 

 the skin is very much higher than that for the exposed nerve- 

 trunks. Thus a stimulus which is to be reckoned a strong one 

 for the exposed nerve-trunk is to be considered a weak one for 

 the surface of this skin. This fact explains the previously de- 

 scribed results. So far the effects have all been those of a weak 

 stimulation, namely, a fall of the blood-pressure. 



If, now, we take steps to secure a considerably greater amount 

 of stimulation by simultane6us scratching of large areas in dif- 

 ferent regions, it is not difficult to satisfy oneself that the same 

 general law applies for the nerve-terminals as for one exposed 

 nerve-trunk. Thus, if we scratch a limited area with a mod- 

 erate degree of vigor, we get a fall, while more violent applica- 

 tion of the instruments to a large area, will give a rise (fig. 19). 



In the last section we compared the effects of stimulating two 

 nerves of the same category but of different sizes, and showed 

 that the nerves of greater size usually surpass those of smaller 

 size in their power of evoking vasomotor reflexes, and referred 

 to Vincent and Cameron's hypothesis that the number of af- 

 ferent nerve fibers is an important factor. In our stimulation 

 of nerve endings, as a rule, we could only apply the stimulations 

 to a small portion of the surface. Now the nerve fibers spread 

 widely from the nerve trunk, and the stimulation of a nerve 

 would be equivalent to the stimulation of the entire surface to 

 which the nerve is distributed. In other words, the stimula- 

 tion of a small portion, e.g., of the skin, corresponds to that of a 



