E. Hindle and N. Cunliffe 
355 
than when the leg is cut off at the coxa. In the latter case, a solid rod 
is produced from the cut end and this rod increases in length, bending 
on itself several times. Subsequently the- rod becomes segmented and 
at the next moult is set free as a perfect leg. When the limb is 
removed nearer the distal extremity a small straight rod is formed, 
' lying inside the last article, and the regenerated part is set free at the 
next moult. 
More recently Friedrich (1906) has given a detailed account of 
regeneration and autotomy in Tegenaria domestica, the common house 
spider. So far as we are aware the only other observations on regene¬ 
ration in Arachnida are those of Loeb (1895), who found that if the 
body of the pycnogonid Phoxichilidium maxillare is cut in two, there 
regenerates from the posterior end of the anterior half a new body-like 
outgrowth. 
Material and methods. 
In the following experiments the tick Argas persicus Oken has 
been employed throughout, mainly because of the ease and rapidity 
with which it can be reared in the laboratory. The ticks were generally 
maintained at 30° C., at which temperature the life-cycle is briefly as 
follows: 
The adult female, after fertilisation, lays a batch of about 60 eggs 
approximately 8-12 days after engorgement; these eggs, after an 
incubation period of about 10 days, hatch out to hexapod larvae. 
The latter, when placed upon a fowl, attach themselves and remain 
feeding for 4-6 days, during which period they increase very considerably 
in size. Finally the gorged larvae drop off the fowl and seek refuge in 
any crevice, and after about 7-12 days moult to eight-legged first stage 
nymphs. 
The first stage nymphs, when placed upon a fowl, gorge themselves 
with blood and drop off within half-an-hour, thus differing markedly 
from the larvae. About 12 days after engorgement they moult to 
second stage nymphs. The latter feed in exactly the same way as 
the first stage nymphs and after a period of about 14-18 days moult 
again, in the majority of cases giving rise to the adult stage. In certain 
cases, however, the tick may pass through more than two nymphal 
stages, but usually the life-cycle of the tick comprises only the stages: 
egg, larva, first and second stage nymphs, adult. The adult tick does 
not moult, but will feed at intervals of about a month and a fertilised 
female generally lays a batch of eggs after each feed. 
