E. Hindle and N. Cunliffe 
357 
of 27° C., but during the experiment the heating apparatus went wrong 
and for some weeks the temperature varied from 15 C C. at night to as 
much as 35° C. during the daytime. This diurnal variation seems to 
have had a marked effect on the subsequent development, for although 
members of the same batch of ticks kept at a constant temperature of 
37° C. all became adult after two nymphal stages, in this experiment no 
less than eight out of the eleven passed through at least three nymphal 
stages. 
Six to ten days after amputation the larvae all moulted to first 
stage nymphs and in none of them was there any trace of regeneration 
of -the lost appendage. All these ticks were reared through the next 
two stages, and the results were fairly uniform. In every case, when 
the animal moulted to the second stage nymph, the second right leg 
was regenerated. The regenerated appendage was perfectly formed but 
was slightly smaller than the corresponding appendage of the opposite 
side. After the next moult, the size of the regenerated limb was 
practically normal. 
Experiment 3. Eleven gorged larvae from the same batch as those 
used in the preceding experiment had their legs amputated on Nov. 7. 
In each case, as before, the second right leg was removed between the 
second and third articles. The ticks were kept at a constant temperature 
of 37° C. Four days later (Nov. 11) nine moulted, none of them showing 
any regeneration. The following day (Nov. 12) the remaining two 
moulted. In one of these there was no regeneration, but in the other the 
animal had regenerated a short l'od-like appendage indistinctly divided 
into three articles. 
All these ticks were raised to the adult state and, apart from the 
above-mentioned exception, the legs regenerated at the next moult and 
were perfectly formed, but slightly smaller than those of the other side. 
The abnormal example however, which had already commenced to 
regenerate previous to the first moult, after the second, regenerated 
a limb perfect both in size and form. 
After the final moult, the regenerated appendages of all the ticks 
were practically perfect. 
A series of controls kept under identically the same conditions showed 
that amputation had no marked effect on the duration of the stages. 
Experiment 4. In this series the legs of twenty-two gorged larvae 
were amputated the day they dropped off the fowl and kept at 37° C. 
Four to five days later they all moulted and in no case was there any 
trace of regeneration. These first stage nymphs were allowed to remain 
