on the Structure of the Mouth in Pediculus. 217 
gans, but with true biting-organs, in the shape of chitinous mandibles 
working horizontally, such as Erichson and Simon have shown to 
exist in P. capitis and P vestimenti, and as I have found myself in 
Phthirius inguinalis.” (Loc. cit. p. 34.) 
Amongst the results of his inquiries the author also mentions 
the following—evidently the most important of them all :— 
‘In the lighter cases, the lice produce merely a papulous exanthema; 
but in more serious cases, they eat their way in large numbers through 
the skin on a circumscribed area, whereby open lice-blains are formed, 
or, if the perforated skin remains over the place, closed lice-blains.”’ 
(L. ¢. p. 41.) 
The verbal tenor of this last passage shows clearly that it is 
principally founded on the recent communications of Dr. Gaulke 
on phthiriasis, communications to which Dr. Landois ascribes 
an extraordinary weight and importance, introducing them as 
he does in the following words :— 
“We are indebted to Dr. Gaulke for recent observations concerning 
phthiriasis, which are in the highest degree important and interest- 
ing (Casper’s Vierteljahrschrift, 1863, vol. xxiii. p. 315), and which 
he has made at Susterburg, near Gumbinnen, on the high road to 
Russia and Poland. In that neighbourhood, which is teeming 
(tiberaus versehen) with lice, he has observed many cases of true 
phthiriasis, of which I will here communicate two, which are of the 
greatest importance.” (. ¢. p. 32.) 
Let us, then, examine these proofs, which Dr. Landois con- 
siders so very important. 
The first of these cases was that of a lame, lunatic, old 
woman. She became to that degree infested with Pediculus vesti- 
menti, of which her lameness and a complete want of nursing 
made her a defenceless victim, that she got a bad exanthema. 
(It is here assumed, without any further proof, that the exan- 
thema was caused by the parasites.) This ‘‘ exanthema” (Aus- 
schlag) consisted of innumerable cavities in the skin, of the 
diameter“of a pea and about a quarter of an inch deep, in which 
cavities there were thousands of P. vestimenti. The habitation 
of the woman, which was dirty and dark, teemed with the ver- 
min, and she did not leave it during the medical treatment. The 
latter remained without sensible effect, and she died of “ phthi- 
riasis externa.” 
The other case was that of an utterly degraded vagabond, 
formerly an artisan. After a prolonged absence from home, he 
returned, full of vermin, in a low and thin condition (animisch 
und kachektisch), with sallow face and thin parchment-like skin. 
On the skin, particularly on the inner side of the limbs, about 
one hundred places were observed, partly open, partly covered 
