220 
Arrjas persicifs 
extended, in succession from behind, forwards, and finally the capitulum 
is depressed into the camerostome. When this occurs, the tick is im¬ 
mersed into a cjuantity of the fixing fluid in a small glass vessel, the 
needle is withdrawn, and the specimen remains therein for such time as 
is necessary to ensure complete fixation. 
The specimens are then thoroughly washed with a suitable medium, 
and after dehydration embedded in paraffin. A short account of the 
procedure which we used is given in Part I (p. 24). 
After fixation in Carnoy’s Fluid, sections were stained in Thionin 
and counter-stained with Eosin or Orange G. If Flemming’s Fluid had 
been used for fixation, Flemming’s so-called “triple stain” (Safranin—• 
Gentian violet—Orange G.) or Heidenhain’s Iron-alum-Haematoxylin, 
was found most suitable. Materials fixed with Kleinenberg’s Picro- 
sulphuric acid or Perenyi’s Fluid were stained with Ehrlich’s Haema- 
toxylin and counter-stained with Eosin, Orange G. or Picric acid. As 
a conti’ast-stain, the latter reagent has the advantage of demonstrating 
the chitinous structures very clearly. 
For the dissections, one of Zeiss’s binocular, image-erecting dissecting 
microscopes was used. The microscopical examination of sections etc. 
was carried out with Zeiss apochromatic objectives and compensating 
oculars and all the figures were drawn with the aid of the Abbe drawing 
apparatus. 
The integument. 
Plate XVII, fig. 1. 
As already stated in Part I of this paper (p. 29), the integument 
consists of an external chitinous cuticle, and an internal liypodermis 
composed of living cells. The hypodermis of A7'gas persicus presents a 
very different appearance to that of the Ixodid ticks. With the ex¬ 
ception of a limited area, it consists of a thin layer of cells with a finely 
granular protoplasm and flattened nuclei. Intercellular membranes are 
not apparent, and in consequence, the nuclei appear to be scattered at 
irregular intervals in a thin protoplasmic lining of the cuticle. The 
exception is the hypodermis which underlies the cuticle of the post- 
genital area, in which part of the body, only, do the hypodermal cells 
exhibit the columnar form which is the rule in the Ixodidae. 
The hypodermal layer is invariably found accompanying the chitinous 
structures; even internal parts such as the invaginated portions of the 
cheliceral sheaths, the cheliceral shafts and the subcheliceral plate, all 
