Action of Tobacco Smoke 357 



elastic tissue stain) ; and (c) silver nitrate, 5 per cent, aqueous solution 

 (v. Kossa's calcium test). The sections were mounted in Canada balsam. 

 Photomicrographs of the three specimens are shown in the accompanying 

 Plate 1 shows extensive fibrosis of the tunica media, invading to a slight 

 extent the tunica intima. It also .shows, in parts, the antecedent stage of 

 ■fibrasis as an inflammation, with plentiful cell-proliferation. 2 shows 

 marked erosion and rupture of the elastic fibres ; some of these fibres are 

 encased in calcium .salts. 3 shows considerable deposits of calcium .salts 

 — which are stained black in this specimen. 



Rabbit A was killed. The animal was found to have tuberculosis of 

 the lungs. The heart and aorta of this animal showed hardly any naked- 

 eye change. The trachea was acutely inflamed, and with the exception of 

 the tuberculous lesions, there were no other abnormalities. 



Sections from the aorta of this rabbit (A) show changes similar to 

 those exhibited by section 1 of rabbit B. 



From these experiments I conclude that it is po-ssible to obtain arterio- 

 .sclerotic changes by the inhalation of tobacco smoke. 



It gives me much pleasure to record my thanks to Dr W. E. Dixon for 

 his advice, and to Dr W. H. Harvey for preparing the photomicrographs. 



VII. General Conclusions. 



1. Nicotine is the most important poison in tobacco smoke. 



2. Pyridine bases, in the quantities in which they are present in tobacco 

 smoke, are not injurious to the .smoker. 



3. Smoking raises the blood-pressure by vaso-constriction, accelerates 

 the heart and respiration, and increases intestinal movements. In excess, 

 cerebral depression may occur, and, with the coexisting depression of the 

 vaso-motor centre, may lower the blood-pressUre to such an extent that 

 collapse may be induced. 



4. The amount of nicotine inhaled during smoking depends not so much 

 on the tobacco smoked, as upon the form in which it is smoked. The 

 greater the condensation area between the point of combustion and the 

 entrance into the mouth, the more nicotine will be inhaled. 



5. Arterial disease may result from prolonged tobacco smoking. 



REFERENCES. 



I 



(1) Langley, Journ. Physiol, xl, p. 262. 



(2) Dixon, Journ. Physiol, vol. xxx. p. 115, 1903. 



(3) Crile, Experimental Research into Surgical Shock (1897). 



