f 
1916-17.] Observations on the Blood in Gas Poisoning. 307 
pulse. On substituting air for the mixture of air and chlorine, respira- 
tion returns immediately to the normal, while the blood-pressure rises 
temporarily to a much greater height than normal. 
A second period of inhalation produces the same results at the end of a 
longer period, but usually leads to the death of the animal. 
Administration of a 2 per cent, chlorine mixture produces similar effects, 
with a cessation of respiration, which are not recovered from. Artificial 
respiration has no effect. With a mixture of 5 per cent, or greater con- 
centration a fatal result is rapidly and inevitably produced. 
Schafer considers that these effects must be due to a local effect 
on the lungs, since the chlorine which is inhaled cannot be carried to 
the tissues in a free state. Moreover, there is evidence, in animals killed 
in the above manner, that there is no poisoning of the tissues, because 
their muscles contract briskly and the heart responds to stimulation. 
The only visible change is in the lungs. These, even after the shortest 
exposure to a fatal dose, are intensely red, and distended ; they possess 
a solid feel, and are not crepitant, although small pieces still float. In 
Schafer’s opinion the fatal result is due to obstruction in the pulmonary 
capillaries, which makes it impossible for the blood to pass freely to the 
left side of the heart. There is apparently not only no constriction of 
the bronchioles, but experimental methods indicate that they are actually 
more permeable. 
Microscopic sections show the pulmonary capillaries engorged with 
blood ; there is oedema of the interstitial tissue and of the air vesicles. 
Probably the oedema is due to the vascular obstruction. It is significant 
that the epithelium of the bronchial tubes is well preserved. 
Leonard Hill ( British Medical Journal , 1915, ii, 801) confirms Schafer’s 
results in the main, but does not consider that death is due to stasis in 
the pulmonary vessels. He believes, on the contrary, that obstruction in 
the air passages, through contraction of the bronchial muscle, bears an im- 
portant part in the symptoms, and further suggests that Schafer’s results 
may have been due to the relatively high concentration of the gas which 
he employed in his experiments. He interprets the sequence of events in 
the lung as follows : — Just as lymph is poured out after a superficial burn 
of the skin, or the application of a blistering fluid, or in a septic wound 
under the influence of bacterial toxins or antiseptics, so an exudation of 
lymph in the lungs is excited by the action of chlorine. The epithelial 
lining, both that of the mucous membrane and of the capillary wall, is 
damaged by the poison, and fluid is withdrawn, by osmotic forces, from the 
damaged vessels. In short, the classical phenomena of inflammation are 
