218 
Arcfan 2)€i\sicus 
Living ticks may be dissected under normal saline solution and the 
movements of the heart and the alimentary canal observed; or for the 
examination and removal of portions of the living organs etc. for 
sectioning. An objection to such dissection, and this applies also to 
the dissection of ticks which have been merely killed with chloroform, 
is the fact that in making the first incision through the cuticle, it 
is almost impossible to avoid wounding the more or less distended 
alimentary coeca, with the result that the ingested blood is constantly 
oozing and obscuring the dissection. If the tick is first killed by 
momentar}' immersion in boiling water, the contents of the gut are 
coagulated and the subsequent operations are thereby facilitated. This 
procedure, of course, makes it impossible to use the specimen so treated 
for the study of histological details, but, in our opinion, removal of 
organs or portions of organs, or partial dissection of the tick as a pre¬ 
liminary to histological fixation is unde.sirable. The handling of the 
tick induces strong contractions of the dorso-ventral body muscles and 
owing to the pressure thus created in the body cavity, extrusion and 
consequently displacement of the organs take place, immediately the 
pressure is released by the incision. Provided certain precautions are 
taken, it is not a difficult matter to ensure perfect fixation of the 
internal organs without further mutilation than is occasioned by the 
insertion of a hypodermic needle in the manner described below'. 
In addition to congealing the contents of the gut, the boiling water 
treatment leaves the organs, and tissues generally, in a condition suitable 
for dissection, which operation is carried out under water or normal 
saline solution. Alcohol makes the organs very friable and is therefore 
unsuitable, except for special purposes. Dissection from the dorsal 
surface is the most frequently used method, but it .should be borne in 
mind that dissections from the lateral and ventral aspects are also of 
the greatest use. After the tick is fixed in the dissecting dish and 
covered with liquid, a small incision is made at the posterior margin of 
the body. The dorsal integument is then gently raised with fine-pointed 
forceps and the cuticle divided progressively, with a mounted needle 
ground to a cutting edge, along both lateral margins at the line of 
junction between the dorsal and ventral integument, where the cuticle 
parts readily. As the flap of skin is gradually reflected forwards, 
muscular and connective tissue attachments on its under surface are 
divided as they come into view. 
Most of the errors of the earlier w'orkers on the anatomy of ticks are 
the outcome of observations made from dissections alone, and, useful and 
