[ 22 ] 
The contents of the tumour consist mainly of granular debris and 
ca careous particles. The tumour also contains the head of the female 
worm, and one or more males curled many times round themselves. They 
may easily be pulled out of their loose surroundings. When males are 
present the granular debris, if mixed with a drop of normal salt solution, 
shows a large number of free embryos. 
The portion of the female hidden inside the tumour is the narrow head 
end. On its entrance it receives a firm fibrous sheath from the lining of the 
tumour which is somewhat difficult to dissect off. The size of the worm 
tapers gradually, as it is traced forwards until at the mouth it is not more 
than .5 mm. in diameter. 1 he tough sheath surrounding the worm is firmly 
attached to the fibrous walls of the tumour but is lost towards the head, so 
that this part of the worm, much narrower than the other parts, is at liberty 
to move about amongst the granular debris. 
Once the sheath is removed the rest of the worm will come off readily. 
he ensheathed portion is bent on itself and usually assumes the form of a 
letter S. 
The portion bound down by the sheath measures about 5 mm., forming 
a fixed collar round this part of the worm whilst the free head portion 
reaches a length of 20 mm. The part of the worm inside the tumour thus 
measures about 25 mm. 
Section of Aortic Tumour. 
Sections of the aorta with attached tumour both transversely and longi¬ 
tudinally to the points of entrance of the worm demonstrate the following 
points:— 
The epithelium which lines the outer surface of the tumour consists of 
a layer of flattened cells continuous with the endothelium of the intima. 
Just at the angle where it actually merges into the intima this layer is much 
thickened, thus forming a triangular area, but the cells still maintain their 
flattened character. 
Beneath this endothelial layer is a dense mass of cells irregularly distri¬ 
buted and bound together by some thin bands of fibrous tissue. The nuclei 
of the cells nearest the surface are deeply stained, whilst those lower down 
are more or less degenerate in character, and here and there a few strands 
of elastic fibres (stained yellow with Van Gieson) may be encountered. 
Amongst this loose granular tissue the worm is often seen cut 
trans\ ersely. \\ hilst thus in situ , its structure may be studied with greater 
ease than in a specially prepared one obtained from the dissected out'worm. 
The tumour is separated from the middle wall of the aorta by a thin 
band of elastic tissue which extends from one end to the other. The minute 
structures of the aorta differ somewhat markedly from those of a healthy one. 
Instead of the long continuous bands of elastic tissue interspersed between 
the fibrous strands in the tunica media one meets with short bands arranged 
ii regularly throughout, and on the whole there is less elastic tissue in the 
layers of the morbid aorta than in the normal one. 
The point of entry of the worm, as seen in a section of the tumour cut 
parallel to the worm, possesses no special significance. The sheath encircling 
the worm is well marked as a deeply stained fibrous band, and surrounding 
this are the usual loose granular masses composed of living and degenerate 
cells. 
