88 Biology 



to relate even such destructive infestation often fails to attract the 

 attention of the owner to the pest. The losses are most striking when 

 a fowl house is first occupied after having stood empty for a few months, 

 as frequently happens in and about towns. The hungry ticks swarm to 

 the birds and may kill half or more of them before their presence is 

 discovered." 



Reaney (1907), in Central India, saw fowls die within 24 — 48 hours 

 from intense infestation with persicus, after being placed in a fowl house 

 which had been disused for a fortnight. He attributed the death of the 

 birds to a poison emanating from the tick and noted that the bites 

 produced extensive extravasations of blood beneath the wings. 



From the foregoing it appears reasonable to conclude that persicus 

 may kill animals by massive infestation comparable to the "tick worry" 

 seen in cattle infested with Ixodidae. Apart from this there appears 

 to be evidence pointing to the ticks giving off some poisonous substance 

 into the wounds they inflict, and evidence in this respect will be also 

 found in the notes relating to other Argasidae. Experiments conducted 

 in the laboratory at Cambridge have recently proved that the salivary 

 glands of A. persicus contain a substance which retards or prevents 

 blood coagulation, i.e. anticoagulin (Nuttall and Strickland). Again it is 

 a not infrequent occurrence that tick bites become secondarily infected, 

 the wound serving as a point of entrance for pathogenic bacteria. Finally 

 we know that some Argasidae and Ixodidae may transmit certain 

 blood parasites to their hosts in the manner considered below for the 

 Argasidae. 



Argas persicus in Relation to Disease. 



Spirochaetosis in Fowls is a disease whose cause, the Spirochaeta 

 marchouxi 1 , was first discovered in Brazil by Marchoux and Salimbeni 

 (1903). The disease may be very fatal, since it is capable of destroying 

 all the fowls in a yard in the course of a few days. The disease begins 

 with diarrhoea, followed by loss of appetite, the birds appearing som- 

 nolent; the feathers being ruffled and the comb pale. The birds cease 

 to perch, lie down with the head resting upon the ground, and death 

 takes place during a convulsive attack. At times the disease runs a 

 slower course, the legs become paralysed, then the wings, and the bird 

 grows thin and dies in 8 — 15 days. Recovery may take place, but it 

 is rare after paralytic symptoms have appeared. At autopsy, during 

 the acute period of the disease, the spleen appears much enlarged and 

 1 Sp. marchouxi Nuttall, 1904, p. l& = Sp. gallinarum Blanchard, 1905. 



