MECHANISM OF SHOCK. 393 



ture. This symptom is considered of great diag- 

 nostic value when the drop amounts to 2 or 3 C. 

 and other experimental conditions are constant. 



In dogs, the symptoms vary greatly from those 

 in guinea-pigs. Here a characteristic fall in blood 

 pressure is found. Vomiting, involuntary urina- 

 tion and defecation, paralysis and narcosis are 

 common symptoms. 



The respiratory mechanism of shock in guinea- 

 pigs, according to Auer and Lewis, is that of a 

 spasmodic contraction of the unstriped muscle of 

 the bronchioles resulting in obstruction of the 

 lumen, acute emphysema and death from asphyxi- 

 ation. 



Section of the vagi does not influence this pul- 

 monary phenomena, indicating that the effect is 

 a peripheral one. Schultz has shown that the 

 unstriped muscle fiber of a sensitized guinea-pig 

 contracts more vigorously when specific serum is 

 applied directly to it than when other serum is 

 used. Atropin, which acts on the nerve endings, 

 causes an inhibition of symptoms. Marked con- 

 gestion of the abdominal blood vessels is a com- 

 mon finding at autopsy. Various hypnotic and 

 narcotic drugs have been described as inhibiting 

 anaphylactic symptoms, but the effect seems 

 mainly due to a masking of symptoms. 



A sensitized animal which has recovered from a 

 non-lethal toxic dose of protein is refractory to 

 the action of a later dose. The condition of such 

 an animal is known as antianaphylaxis, and it 

 has been demonstrated by failure to produce pas- 

 sive anaphylaxis by using the serum of an animal 

 in a state of antianaphylaxis, that the condition 



