456 
Biolodn of Txoflulae 
great powers of fasting, for of 575 specimens only 84 had died by the 
569th day, the survivors being still fairly lively when disturbed; the 
$s appear to be even hardier than the ds in this respect. Variation : 
Cunliffe (1914, Parasitologi/, vi. 372-378) working in my laboratory, has 
shown that small and large forms may readily be raised experimentally 
according as the nutrition of the immature stages has been more or less 
interfered with; he has figured the tick in all its stages. 
Under the most favourable conditions, notably at a temperature of 
30° C. during the period of metamorphosis, the life-cycle may be com¬ 
pleted in 63 days; in nature the period may be indefinitely prolonged, 
depending upon temperature and the ability of the tick to find a host. 
The part played by R. sanguineus in the transmission of canine 
piroplasmosis is referred to on p. 449. 
