474 THE RESPIRATORY MECHANISM. 



occur in the lungs remained doubtful notwithstanding the 

 labors of Brown-Sequard, Hofmokl, Lichtheim, and others, 

 until 1881, when Frangois-Franck was able to demonstrate a 

 vasoconstrictor action of the sympathetic nerves distributed to 

 this organ. Since then Cavazzani, Henriquez, and Rose Brad- 

 ford and Dean have confirmed the latter investigator's observa- 

 tions. The experiments of Franc, ois-Franck 34 consisted in 

 stimulating the sympathetic fibers at their entrance into the 

 organ: i.e., the fibers to which we have applied the term "ex- 

 trinsic." This investigator found that increase of pressure 

 occurred above the area stimulated, while decrease of pressure 

 simultaneously became manifest below the latter. This test, 

 as is well known, is used to determine the existence of vaso- 

 motors in other organs. Again, he noted that moderate stimu- 

 lation of the sympathetic cardio-pulmonary filaments caused 

 lowering of the pressure in the left auricle and increase in the 

 pulmonary artery: a result indicating a vasoconstrictor action 

 upon the intervening vessels. 



Further testimony appears when in accord with previously 

 recorded facts we connect the effects observed, not with the 

 sympathetic ganglionic chain per se, the conducting path 

 from the anterior pituitary to the adrenals, but with the 

 spinal cord. The experiments of Eose Bradford and Dean 35 

 are thus referred to by Frangois-Franck: "They carefully 

 sought the points of emergence, from the cord, of the filaments 

 which cause elevation of pulmonary pressure and lowering of 

 aortic pressure: that is to say, pulmonary vasoconstriction. 

 These were located from the second to sixth dorsal, and, in 

 respect to maximum effects, on a level with the third, fourth, 

 and fifth nerves. The pulmonary vasoconstrictors ascend the 

 chain up to the first thoracic ganglion, where they become de- 

 tached, to reach the pulmonary plexuses." A suggestive feat- 

 ure of the topography of these nerves is that the lower limit 

 of the ganglionic chain through which they pass happens to 

 be the upper limit of the ganglia from which the splanchnic 



84 FranCois-Franck: Lalesque, These de Paris, 1881; and Archives de Phy- 

 siologic, Oct., 1895. 



86 Rose Bradford and Dean: Journal of Physiology, p. 57, 1894. 



