G-. H. F. Nuttall and C. Strickland 
309 
It follows that the anticoagulin is destroyed by an exposure for 
10 minutes to a temperature of 80° C. and that its activity is reduced by 
lower temperatures, being considerably reduced even by a temperature 
of 55° C. 
Conclusions. 
1. There is clinical and experimental evidence that the bites of 
Argasidae may be occasionally followed by toxic effects which are either 
local or general in character. 
2. This toxic effect may be due either to the peculiar susceptibility 
of the individual upon whom the bite has been inflicted or to the 
character of the substances injected into the wound by the tick in the 
act of biting. The cause of the toxic effect remains to be discovered. 
3. The bodies of Ixodes ricinus contain substances which prevent 
the coagulation of the blood and cause toxic symptoms when injected 
into dogs. These substances do not cause haemolysis (Sabbatani). 
4. The salivary glands and intestines of A. persicus contain anti¬ 
coagulin but no haemolysiu. 
5. The amount of anticoagulin present in the salivary glands of 
A. persicus varies considerably. The amount contained in the glands of 
a single tick may delay the coagulation of '02 c.c. of human blood for 
45 to 95 minutes or indefinitely. The anticoagulin also acts on rabbit’s 
blood. 
6. The movements of human leucocytes remain unaffected by 
exposure to emulsions of the salivary glands of A. persicus. 
7. Excepting the effects due to the presence of anticoagulins, it has 
not been established that the bodies or salivary glands of A. persicus 
contain toxic substances. 
8. The anticoagulin in the salivary glands of A. persicus is 
destroyed by an exposure of 10 minutes to a temperature of 80° C. Its 
action is partially abolished by a similar exposure to 55° C. 
Note whilst going through the press. 
We have omitted to mention an interesting observation by 
Christophers (1906, p. 45) with regard to the fluid excreted from the 
“coxal glands” of Ornithodoros savignyi. Christophers casually remarks 
that “ the fluid is slightly alkaline and prevents the coagulation of the 
