314 Genus Ixodes 



by Railliet, 1895) says the bite may produce gangrenous inflammation 

 in sheep, whilst in man the bite may be followed by abscess, oedema, 

 lymphangitis, etc., accompanied with febrile symptoms. Cao (1898) made 

 a few experiments with ricinus and B. anthracis and Staphylococcus. He 

 removed these ticks from the ear of a small dog and inoculated their 

 contents, with negative results, into another dog, as well as into a 

 rabbit. He then injected a mixed culture of Staphylococcus pyogenes 

 aureus and albus into the jugular vein of the same dog and removed the 

 ticks at intervals of 12-36 hours, making plate cultures of their contents. 

 He found cocci in the ticks after 12 hours had elapsed since the injection. 

 After 16 hours they were very numerous ; after 20 hours less so ; after 24 

 hours they had disappeared from within the ticks. In a second experi- 

 ment he injected B. anthracis into the jugular vein of a dog and removed 

 the ticks at intervals of 4-48 hours, plating their contents. His results 

 in this case were negative, that is, no anthrax bacilli grew upon the 

 plates. It is evident from the first experiment that bacteria circulating 

 in the blood may gain access to the body of the tick, but there is nothing 

 to prove that ticks are capable of communicating a bacterial infection. 

 Megnin (1892, pp. 26-28) denied that any ill effects followed the bites 

 of ricinus. Although this is incorrect, it is certainly the rule that 

 little injury follows the bite, and a tick may hang on for days without 

 being perceived. 



Penetration of Ixodes ricinus beneath the skin : For reasons which we 

 do not at present understand the tick in the larval, nymphal or adult 

 ( °. ) stage may occasionally penetrate beneath the skin of the host 

 and cause local injury. A number of instances are recorded in the 

 widely scattered literature, as follows : 



Dubreuilh (1838, cited by Nuttall, 1899) reported the presence of 

 ricinus in a pustule in the mastoid region in man. Trillebert (1863, 

 Ric. vitirin., cited by Megnin, 1892) observed a cyst at the end of a 

 dog's ear which contained a tick supposed to be ricinus. Vau Beneden 

 (1883, p. 142) recorded the penetration of (?) ricinus beneath the skin 

 in man and regarded it as a normal occurrence. Aurivillius (1886 b, 

 p. 139) records the presence of ricinus beneath the skin of a fox. 

 Blanchard (1891, p. 689) describes a much-quoted case of a tumour of 

 the size of a nut on a man's abdomen. The tumour had the feel of a 

 sebaceous cyst, there was no external lesion of the skin to be seen 

 and the tumour had existed some weeks. On opening the tumour a 

 female ricinus 8 mm. in length and in a living condition was discovered. 



