35G Regeneration in Argas persicus 
In our experiments the ticks were kept in glass-topped pill-boxes 
containing filter paper and were maintained at any desired temperature 
in incubators. The amputation of the various parts of the legs, a matter 
of some difficulty in the smaller stages, was best effected by placing the 
tick, in its normal position, on a piece of card under a binocular dis¬ 
secting microscope; the limb, or part of the limb, was then removed by 
means of a fine needle ground to a knife-edge, the tick being kept 
stationary by means of a camel-hair brush. During this operation 
it is essential that no considerable pressure should be applied to the 
body of the tick, as in this case the loss of coelomic fluid is so great that 
the animal dies. 
Larva. 
Our experiments with the larvae may be divided into two groups. 
In the first instance we used ticks that had gorged themselves and 
dropped off the fowl, but later we adopted the plan of cutting off the 
legs whilst the larvae were still attached. The results of the first series 
of experiments were mainly negative, and this is noteworthy since, 
according to most theories of regeneration, the younger stages should 
possess greater regenerative power than the older. The results of the 
first group are as follows: 
Experiment 1. A number of larvae, placed on a fowl on May 25th, 
dropped off gorged on the 29th and 30th, and were kept at a temperature 
of about 27' J C. On June 3rd the second right legs of five of these 
larvae were amputated and the ticks kept at the same temperature. 
Two days later one of these larvae (a) moulted and possessed a 
normally-developed second right leg, with the exception that the tarsus 
was very imperfect. The other four ticks moulted respectively, two on 
the third and one on each of the fourth and sixth days after the 
operation; in none of these was there any trace of regeneration. Since 
in larva (a) only two days had elapsed between the amputation and the 
moult, it seems probable that the immature nymphal leg had already 
been formed within the skin of the larval leg and partly withdrawn; 
therefore the needle had only passed through the tarsus, and this 
portion of the limb was not regenerated. 
Experiment 2. A number of larvae were placed on a fowl on 
November 3rd and dropped off gorged on the 7th. The same day 
(Nov. 7th) the second right legs of eleven of the gorged larvae were 
cut off, in every case the four or five distal articles being removed. 
These ticks were kept in an incubator supposedly at a temperature 
