'94 
Wisconsin Academy of Sciences, Arts arid Letters. 
Mantis Carolina , L. 
(Plate II, Fig. 11.) 
Mr. T. H. Morgan has kindly sent me some of the embryos of this inter¬ 
esting insect. All the specimens examined were in a stage just preceding 
the rupture of the embryonic envelopes, hence almost corresponding with 
the Blatta embryo figured (Fig. 1). The pleuropodia are distinctly visible 
in surface view as a pair of narrowly pyriform evaginations, partly covered 
by the metathoracic legs with which they are liomostichous. Their tips are 
directed laterally, while the ends of the metathoracic appendages converge 
towards the median ventral line. Each pleuropodium is very much shorter 
and narrower than the legs or any of the cephalic appendages. A section [Fig. 
11] shows that the organ is a solid body, perhaps best described as a narrow, 
pear-shaped sack, whose thickened walls are made up of a single layer of 
cells and whose cavity has been reduced so as to be represented by a line. 
The cells forming the appendage have the form of curved pyramids; their 
broad bases form the outer surface and their gradually tapering apices 
converge from all sides towards the central line representing the obliter¬ 
ated cavity. These cells differ only in shape from those of the ectoderm of 
the body walls and other appendages: the size and reactions of the nuclei 
together with the quantities of cytoplasm surrounding them are essentially 
the same in the elements of both the body walls and pleuropodia. In the 
pleural wall [ecd] the nuclei are arranged in about three irregular rows; 
just at the insertion of the pleuropodium, however, there is only one row, 
a fact indicating that the appendage, which was very probably hollow in a 
preceding stage, had its lumen shut off from the body cavity by the in¬ 
trusion of a layer of ectoderm cells at x. Not having studied more ad¬ 
vanced embryos, I am unable to state anything in regard to the manner in 
which the pleuropodia degenerate. The fact that these organs are small 
and solid and that their component cells differ in no way from the ecto¬ 
dermic elements of the body walls and other appendages, is sufficient proof 
that the pleuropodia of Mantis are mere rudiments. 
In Mantis Carolina there are distinct appendages on at least the second, 
third and fourth abdominal segments, but none of these in my embryos 
had developed beyond the mammillate stage. Graber [’88] has observed 
on the second abdominal segment of an European Mantis a pair of append¬ 
ages shaped very much like the pleuropodia on the basal segment. As 
these do not occur in all embryos of the European species, and as the embryos 
of the American species examined by me, were all taken from a single 
capsule and hence deposited by a single female, I cannot feel certain that 
this second pair of pleuropodia is always or even normally absent. 
