22 
Regeneration in Ticks 
results in respect to regeneration for the reasons specified on pp. 17 and 23. It is 
noticeable that after operations on larvae the hypostome is regenerated better 
than the digits, whilst mostly no attempt at regeneration takes place in the 
palps. 
When the first-stage nymph has its mouthparts amputated, the hypostome 
is best regenerated, then follow the digits, whilst the palps are least well 
regenerated. 
This order changes, however, when operations are made in the second- 
stage nymphs , for the succeeding stage (adult or third-stage nymph) shows 
regeneration to have taken place best in the palps and digits and least well 
in the hypostome. The cause of this phenomenon requires elucidation. 
The foregoing tabular summary shows, moreover, that as the tick de¬ 
velops toward maturity, the power to regenerate the palps and digits 
increases, there being no distinct difference in respect to the hypostome, 
although the proportion of perfect to slightly imperfect hypostomes in 
second-stage nymphs after operation is highest, i.e. 15 : 20. 
Amblyomma hebraeum. 
Operations on larvae, consisting of basal amputations of palps and hypo¬ 
stome, were followed in the nymph by perfect regeneration in all cases (ten 
operations); amputations of digits and twice their length of cheliceral shaft 
had no effect, but in one case, where a longer piece of shaft was removed 
(Amblyomma 5), the shaft appeared shorter than normal in the nymph. 
Operations on nymphs, consisting of basal amputations of palps and 
hypostome or of digits with four times their length of shaft, were followed 
by complete regeneration of all parts in the adult. 
Hyalomma aegyptium. 
Operations on nymphs (ten specimens) wherein the palps and hypostome 
were amputated at or near the base, were followed by perfect regeneration 
of these parts in the adult. Amputations of the digits and 2-3 times their 
length of cheliceral shaft, only resulted in deformity of the digit in one case 
(Hyalomma 3), whereas, when more of the shaft was removed (Hyalomma 8), 
the digits appeared badly deformed in the adult. 
The results obtained after amputations of mouthparts in the Ixodid ticks 
are therefore in strong contrast to those in Argas. Regeneration takes place 
equally well after operations on larvae and nymphs. Perfect regeneration 
followed on almost all operations, i.e. 27 hypostome amputations, 23 palp 
amputations and 40 amputations of digits; slight deformity of digits followed 
three operations, great deformity in two, and in but one case was the cheliceral 
shaft shortened through mutilation. 
