on the Structure of the Mouth in Pediculus. 219 
munications of Dr. Gaulke, has found several particulars too 
open to criticism. He rejects most properly the idea of the 
ovipositor “sehr energisch,” and consequently rejects at the 
same time Dr, Gaulke’s whole theory of the formation of the 
abscesses; he marks the account of the dry abscesses with a 
note of exclamation ; and where Dr. Gaulke speaks of the inter- 
nal use of cod-liver oil, Dr. Landois suggests “ that the external 
use might probably be more effectual.” But without consider- 
ing that the dry abscesses are equally worthy of a note of excla- 
mation whether they are assumed to have been caused by a sting 
or dug by the insect by means of its mandibles, Dr. Landois 
nevertheless persists in pronouncing Dr. Gaulke’s relation of 
cases of phthiriasis to be “ of the greatest importance, because they 
place many dark points in the history of phthiriasis in their proper 
light.”” And thus the present examination of this matter is again 
brought back to its starting-point. For so much must here 
become evident, that, if Dr. Landois finds such highly impor- 
tant information and great discoveries in these communications 
of Dr. Gaulke’s, this is solely because he has allowed himselt 
to be blinded by the prospect that, in spite of their manifest con- 
fusion and untrustworthiness, these communications might serve 
to procure for the new theory of the structure of the mouth m 
the louse serious consideration and final victory. 
Let us therefore return to Krichson and Simon’s, and Dr. 
Landois’s own account of the organs of the mouth in these ani- 
mals, and we shall in that respect find their drawings very 
useful *, 
Whilst Swammerdam, step by step, shows us the way by which 
he has come to his final conclusion, our three authors leave us in 
entire ignorance how they have carried on their investigations. 
However, it is not difficult to find out their method, which a few 
experiments will prove to have been the simplest that could pos- 
sibly have been adopted for the examination of such objects. It 
is only necessary to cut off the fore part of the head, place it under 
the microscope covered with a thin glass, and press it hard, and, 
if the magnifying-power used is considerable, the figure given 
by these authors on their plates will immediately present itself. 
A long dark object is discernible lying longitudinally imside the 
head, and provided at its anterior extremity with some smaller 
appendages, which appear to vary in a curious way as to num- 
ber and position. Sometimes they resemble diminutive hooks, 
as in Dr. Landois’s figure ; but if the experiment is oftener re- 
peated, they will sometimes arrange themselves into two rows, as 
if we had a pair of slender articulated appendages before us, 
* A copy of Erichson and Simon’s figure is inserted in p. 227. 
