618 ANNUAL. KEPORT SMITHSONIAN INSTITUTION, 1911. 



Filipow ' found weak concentrations had no effect on men or ani- 

 mals, while a higher concentration of ozone caused irritation of the 

 respiratory tract. 



Schultz 2 confirmed this irritative effect, and found long-continued 

 breathing of ozone caused pathological changes, particularly in the 

 lungs, which were the cause of death. Schultz considered that the 

 ozone passed into the blood and injured the lung secondarily. Bohr 

 and Maar 3 overthrew this supposition by the ingenious experiment 

 they devised of making one lung breathe ozonized air and the other 

 normal air. They found this lung remained normal while the 

 ozonized lung became oedematous. 



Using a concentration of ozone which produced no visible change in 

 the pulmonary structure, these observers found that it caused a 

 diminished uptake of oxygen; the other lung compensated for the 

 deficiency by an increased uptake. This occurred in both cold- 

 blooded (tortoise) and warm-blooded animals. In the former the 

 initial effect of ozone was occasionally a slightly increased oxygen 

 uptake. If the inhalation of ozone were continuous the increased 

 uptake by the lung ventilated with normal air finally fell away and 

 became deficient; this occurred sooner in the mammal than in the 

 tortoise. 



The C0 2 output was also diminished, but not so markedly as the 

 oxygen uptake, thus the respiratory quotients often rose over 1. The 

 effect of ozone on the respiratory exchange came on gradual^, and 

 with weak concentrations often reached its height after the cessation 

 of the ozone inhalation — there was, in fact, an after-effect which took 

 some little time to pass off. The effect was not modified by a pre- 

 liminary division of the vagi and pulmonary sympathetic nerves. 



The blood of the ozonized animal had no toxic effect when trans- 

 fused into another. Bohr concluded that the effect was primarily 

 on the lungs, and as the oxygen uptake was affected more than the 

 C0 2 output, he claimed that his results supported his view that the 

 pulmonary epithelium by its secretory activity controlled the passage 

 of the respiratory gases. Butte and Peyron 4 likewise record that 

 ozone when inhaled diminishes the metabolism. 



One of the obstacles in the way of investigation has been the diffi- 

 culty of obtaining pure ozone free from oxides of nitrogen, and 

 another has been the want of an accurate method of estimating the 

 concentration of ozone. There has been devised lately an ingenious 

 apparatus for producing ozone, which eliminates the production of the 

 oxides of nitrogen, and allows the ready use of ozone for bleaching, 

 sterilizing water or ventilating purposes. The ozone is generated by 



i Arch. f. d. Ges. Physiol., vol. 34, p. 335. 



2 Arch. f. exper. Path., 1882, vol. 29, p. 364. 



a Skand. Arch. f. Physiol., 1904, vol. 16, p. 41. 



« Comp. Rend. Soc. Biol., vol. 46; Progres Mgdical, 1894, No. 30, p. 61. 



