20 
Regeneration in Ticks 
regenerated. The hypostome , when amputated at any point short of its base, 
is perfectly regenerated, but if cut at its base the regenerated hypostome may 
be slightly deformed (Fig- 3 A). It should be noted that slight asymmetry 
and irregularities of dentition occur in all stages normally. The digits of the 
chelicerae are usually deformed to a varying degree (Fig. 4 D, K, L), the greatest 
deformity or even their non-regeneration may be caused by cutting off any 
considerable length of the shaft (Tick 14, Fig. 4 M); slightly deformed digits 
may function well enough for purposes of feeding. 
First-stage nymphs, when mutilated as described in the case of the larvae, 
vield second-stage nymphs whose structures are affected as follows: the 
palps may appear like the stumps above described, they may be partly re¬ 
generated ( Argas 28, 33, 53, 59), they may be completely regenerated whilst 
appearing short but about as broad as normal ( Argos 32, 43), or they may 
appear normal. The hypostome in most cases is perfectly regenerated, but at 
times it is emarginated distally, an appearance occasionally met in ticks that 
are presumably normal. The digits of the chelicerae may be regenerated per¬ 
fects, or they may be undersized or deformed even when a length of shaft 
only equal to one or two digit-lengths is removed at operation. Slightly 
deformed digits do not prevent the mutilated ticks from feeding normally. 
The whole series of second-stage nymphs, when left unmolested after the 
first operation, and adequately fed, gave rise to normal adults (19 specimens) 
or third-stage nymphs (two specimens) at the next moult. 
When the basis capituli was cut across in first-stage nymphs only four out 
of ten of the ticks survived, the operation being accompanied by a great loss 
of coelomic fluid. None of the survivors moulted normally. In one case the 
basis capituli was not regenerated ( Argos 51), in only one case was there an 
abortive attempt to regenerate a palp (Argos 54, Fig. 3 B and B'); the hypo¬ 
stome was not regenerated, at most, in one case it was represented by a smooth 
stump ( Argas 50); the sheaths of the chelicerae were regenerated, they ter¬ 
minated either with apparently normal digits (Argas 60), small or deformed 
digits (Argas 54, Fig. 3 B), or they were devoid of digits (Argas 50, 51), these 
differences depending no doubt upon the degree of mutilation to which the 
parts had been subjected according as they were more or less protruded when 
amputated. 
Second-stage nymphs , when mutilated, yielded adults (three specimens) or 
third-stage nymphs (five specimens) at the succeeding moult. In these the palps 
were all perfectly regenerated, in one tick the palp had been amputated 
basallv. The hypostome, cut across basally, was perfectly regenerated in five 
cases, it appeared emarginated and asymmetrical in two, and in only one case 
did it subsequently develop to a toothless spine (Argas 67, Fig. 4 H). The 
digits of the chelicerae were regenerated perfectly in all but one case (Argas 70) 
wherein the external article of the digits appeared somewhat small. Only 
one of these ticks refused to feed (Argas 67 above referred to) and those that 
emerged as third-stage nymphs were subsequently raised to perfect adults. 
