G. H. F. Nuttall and C. Strickland 
307 
Experiment with Rabbit’s blood. 
Experiment VI. A similar result was obtained with rabbit blood. 
The blood contained in the control tube clotted in 8 minutes, that in 
the tube containing salivary gland emulsion only clotted after 75 
minutes. 
From these experiments we conclude that the salivary glands of 
A. persicus contain a substance which prevents coagulation of the 
blood. The stronger the emulsion of gland the greater is the anti¬ 
coagulant action. The amount of anticoagulin in the glands of different 
ticks varies considerably (Experiment II) and bears no relation to the 
size of ticks measuring 5 5 to 7'2 mm. in length. The amount of 
anticoagulin present in the glands will doubtless be found to depend 
upon the state of functional activity of the organs. The amount of 
anticoagulin present in the glands of a single tick is sufficient to 
prevent the coagulation of '02 c.c. of human blood for 45 to 95 minutes, 
or even longer. The salivary gland emulsion exerts no inhibitory effect 
on the movements of leucocytes in extravascular blood and neither does 
it exert any haemolytic effect upon the red blood corpuscles. 
Experiments made with emulsions of the intestines and human blood. 
Having established the fact that anticoagulin is present in the 
salivary glands of A. persicus, it remained to be determined if anti¬ 
coagulin is present in the intestines. 
Experiment VII. The intestines of 3 A. persicus were dissected out, 
rinsed in salt solution, emulsified in a small drop of salt solution which 
was mixed in the proportion of 1 :4 with blood. 
Clotting was delayed for 2 hours. The corpuscles were not haemo- 
lysed. It is evident from this experiment that anticoagulin is present 
in the tick’s intestines, and that haemolysin is absent. 
Experiments in vivo. 
It having been stated by Alt (1892, cited by Nuttall, 1899, p. 46) 
that an emulsion prepared by crushing 3 Argas reflexus produced 
toxic effects in a dog (comparable to those produced by small amounts 
of snake venom) on subcutaneous injection, it appeared desirable to 
control this observation. An emulsion of the body contents of 6 
