272 SarCoptic Scabies 
necessary if the mite is to flourish, and the disease may often be cured by no 
other treatment than the supply of nourishing food and generally healthy 
conditions, whereas in man condition, age, sex, temperament, etc., are entirely 
unimportant. Indeed really sick, feverish subjects with serious inflammations 
do not furnish a favourable ground for scabies, which soon dies out upon them. 
Typhoid patients heal spontaneously during their fever, but on convalescence 
the scabies resumes its progress. 
In the life of the male Sarcoptes four stages are recognised, egg, larva, 
nymph and adult. In the case of the female there are two nymphal stages, 
the second nymphal stage being remarkable inasmuch as it is ripe for fertilisa¬ 
tion by the male but has not yet developed the orifice (tocostome) by which 
the eggs are laid. This second nymphal stage is sometimes called the immature 
female (femelle pubere). 
Description of SARCOPTES SCABIEX. 
Adult female. Length 330-450/x; breadth 250-350/x. Body oval and 
testudiniform, being convex above and flattened below; of a translucent dirty 
white colour with the more highly chitinised portions brownish. The integu¬ 
ment is finely striate over most of its surface, the striae being mostly oblique 
on the dorsal aspect, and transverse on the ventral surface. 
There is no definite segmentation of the body, but it is ne\ertheless (in 
the living specimen) fairly clearly divided into two regions by a fold of the 
integument, the division being more distinct ventrally. These two regions 
are generally called the cephalothorax and abdomen, which is, unfortunately, 
an entire misuse of those terms as applied to other groups of Arachnida, as 
the posterior portion bears the last two pairs of legs. The terms notothorax 
and notogaster applied to these regions in their dorsal aspect are peihaps 
less objectionable. Megnin (1895, p. 130) says that the body is divided into 
five incomplete segments by dorsal furrows, and Fiirstenberg evidently is of 
the same opinion. The integument is furnished with an armature of cones, 
spines, scales and bristles which must be carefully studied since they are 
regarded as of great taxonomic importance. 
Dorsal aspect. The fine parallel striae are for the most part absent on a 
large median posterior space (the posterior part of the notothorax and the 
whole of the notogaster) which is beset by about 140 minute conical scales, 
roughly arranged in transverse rows, and with their points directed back¬ 
wards. Fiirstenberg has figured these scales under a very high magnification 
and considers their particular shape characteristic of this species. They are 
mostly of the acorn-shaped variety. (Text-figure 1.) 
On the notothorax there is also a rectangular space free both from striae 
and scales but with a shagreened or rugose surface. This is the claiiieie 
of French and the u Blosse” of German writers, and it is the plastion or 
specially chitinised plate of Megnin, who noted it first in the horse Sai copies, 
where its slightly yellow colour attracted his attention, but found it subse- 
