L. E. Robinson and J. Davidson 397 
Fig. 6. Argas persicus <$ . Sections through the central nervous system, showing the 
disposition of the component ganglia. A. Horizontal section through the supra- 
oesophageal portion, showing the cerebral and cheliceral ganglia; B. Transverse 
section through the same part; C. Transverse section some little distance posterior 
to B, showing the cheliceral and palpal ganglia; D. Horizontal section through the 
suboesophageal portion, showing the palpal, pedal and splanchnic ganglia; E. Vertical 
longitudinal section of lateral portion of “brain,” showing the palpal, pedal, and one 
of the splanchnic ganglia. 
The peripheral distribution of the ganglion cells is clearly indicated in the 
sections, the centrally-situated fibro-molecular substance being represented by 
stippled shading. 
g.cb. cerebral ganglion; g.ch. cheliceral ganglion; g.p. palpal ganglion; g.pd. 
1-4, pedal ganglia; g. sp. 1-2, splanchnic ganglia; n.ch. cheliceral nerve; n.p. 
palpal nerve; n.pd. pedal nerve; n.sp. splanchnic nerve; oes. oesophagus; s.pg. 
periganglionic sinus. 
Parasitology vx 
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