302 
ON THE PRESENCE OF AN ANTICOAGULIN IN THE 
SALIVARY GLANDS AND INTESTINES OF ARGAS 
PERSIC US. 
By GEORGE H. F. NUTTALL, F.R.S. 
and CYRIL STRICKLAND, B.A. 
In the literature relating to the Ixodoidea there are a number of 
cases recorded of injurious effects following the bites of ticks. We do 
not refer to diseases like piroplasmosis and spirochaetosis which are 
known to be tick-traDsmitted, nor to other infective processes which 
may start at the seat of the tick’s bite. The effects we refer to follow 
almost immediately upon the infliction of the bite and are distinctly 
toxic in character. These effects appear to have been more frequently 
observed following upon bites inflicted by species of Argas and Orni- 
thodoros 1 . 
From the fact that strangers to a district are apt to suffer more 
severely than do the natives, it has been concluded that repeated tick- 
bites bring about a condition of immunity similar to that which has 
been observed in the case of mosquito bites. This appears to support 
the view that ticks give off something of the nature of a poison when 
inflicting their bites. On the other hand the toxic effects are by no 
means constant. In fact, in the case for instance of A. reflexus, the 
bites are only occasionally followed by immediate ill effects, and from 
this it has been argued that the persons who suffer possess a peculiar 
susceptibility or idiosyncrasy with regard to the poison. 
It has not as yet been suggested that the differences in the after 
effects of the bite may also be due to differences in the substance 
injected into the wound by the tick. That this suggestion may 
however require consideration is indicated by an observation one of 
us has made with regard to a specimen of 0. coriaceus ($). The 
tick in question was captured in a wild part of Mexico, far removed 
from any human habitations. It is problematical from what source 
1 The literature on the subject has been fully dealt with elsewhere by one of us 
(1899, 1908), and need not be further considered here. 
