DIRECT INJURIES CAUSED BY INSECTS. 45 
which opinion Dr. Bateman concurs with him) that the authors to whom 
he alludes had mistaken for lice some other species of insects, which are 
not unfrequently found in putrefactive sores. 
If these observations be allowed their due weight, it will follow, that a 
disease produced by animals residing under the cuticle cannot be a true 
Phthiriasis, and therefore the death of the poet Aleman, and of Pherecydes 
Syrius the philosopher mentioned by Aristotle, must have been occasioned 
by some other kind of insect. For, speaking of the lice to which he 
attributes these catastrophes, he says that “they are produced in the flesh 
in small pustule-like tumours, which haye no pus, and from which when 
punctured they issue.” For the same reason, the disorder which Dr. 
Heberden has described in his Commentaries, from the communications of 
Sir E. Wilmot, under the name of Morbus pedicularis, must also be a dif- 
ferent disease, since, with Aristotle, he likewise represents the insects as 
inhabiting tumours, from which they may be extracted when opened by a 
needle. He says, indeed, that in every respect they resemble the common 
lice, except in being whiter ; but medical men, who were not at the same 
time entomologists, might easily mistake an Acarus for a Pediculus.? 
Dr. Willan, in one case of Prurigo senilis, observed a number of small 
insects on’ the patient’s skin and linen. They were quick in their motion, 
and so minute that it required some attention to discover them. He took 
them at first for small Pediculi; but under a lens they appeared to him 
rather to be a nondescript species of Pulex*; yet the figure he gives has 
not the slightest likeness to the latter genus, while it bears a striking re- 
semblance to the former. It is not clear whether his draughtsman meant 
to represent the insect with six or with eight legs: if it had only six, it 
was probably a Pediculus ; but if it had cight, it would form a new genus 
hetween the Acarina and the hexapod Aptera. Dr. Bateman, in reply to 
some queries put to him, at my request, by our common and lamented 
friend Dr. Reeve, relates that he understood from Dr. Willan, in conver- 
sation, that the insect in question jumped in its motion. This cireumstance 
he regards as conclusive against its being a Pediculus ; but such a con- 
sequence does not necessarily follow, since it not seldom happens that 
insects of the same tribe or genus either have or have not this faculty ; 
for instance, compare Scirtes with Cyphon, small beetles, and Acarus Scabies 
with other Acari.4 
Dr. Willan has quoted with approbation two cases from Amatus Lusi- 
tanus, which he seems to think correctly described as Phthiriasis. In one 
of them, however, which terminated fatally, the circumstances seem rather 
hyperbolically stated — I mean, where it is said that two black servants 
had no other employment than carrying baskets full of these insects to the 
sea!! Perhaps you will think I draw largely upon your credulity if I call 
1 Hist, Animal. 1, 5. ¢. 31. 
2 rom the terms employed by Aristotle and Dr. Mead in their accounts of these 
cases, it appears that the animal they meant could not be maggots, but something 
bearing a more general resemblance to lice. 
5 On Cutaneous Diseases, 87, 88.; and t.7. f. 4. 
4 Latreille at first considered this as belonging to a distinct genus from the com 
mon mite (Acarus domesticus), Which hé named Sarcoptes; but upon its being dis- 
covered that it also has mandibles, ne suppressed it (1V Dict. d’Hist, Nat, xxi, 
221.); but it has been since resumed by M. Dugts and other authors, 
