THE STRUCTURE OF THE UTERUS. 703 



which is disproportionate to the length of the joint. It is different 

 with the width of the uterus, which increases in proportion as the 

 eggs accumulate within it. At first so narrow that the ova can only 

 lie singly, it continues to grow, till eight, twelve, fifteen, or even more 

 can find room beside one another. It is thus easily explained how 

 the lumen of the uterus is so narrow as it is in young joints, and in 

 the lower loops, even when the joints are mature. 



The wall of the uterus is formed of an apparently very extensile 

 and structureless membrane, the independence of which may be 

 clearly seen in the narrower loops, but which with, increasing width 

 becomes continually more delicate and less readily separable from the 

 surrounding connective-tissue. An epithelium, such as Stieda and 

 Moniez report, is not present, but after hardening, one can not 

 unfrequently detect on the inner surface of the cuticle the finely 

 granular residual traces of the ova. This finely granular substance 

 occurs also between the eggs, and is probably an unused remnant of 

 the yolk. 



The cuticular coat of the uterus is externally surrounded by a 

 cellular layer, whose constituent elements are distinguished from the 

 ordinary connective-tissue cells by their abundant protoplasmic 

 contents, by their smaller size, and by their close grouping. In their 

 appearance and form they sometimes recall the subcuticular cells. 

 In the only moderately distended portions of the canal, they are less 

 sharply defined than in the wider parts, and are so abundantly 

 developed that Eschricht actually regarded the sheath formed by 

 them as a special organ (the capsule of the uterus). Special 

 musculature is only recognisable on the narrowed tubular portion of 

 the uterus, which connects the last loop, lying to the right or left of 

 of the cirrhus -pouch, with the female genital aperture. It consists 

 of a layer of circular muscles, which embrace the canal, and have the 

 effect of forcing the contained ova outwards. One not unfrequently 

 finds single ova still lying within the funnel-shaped opening. Their 

 transmission into this expelling apparatus, like the forward move- 

 ment through the uterus, is, apart from the vis a tergo, effected by 

 the pressure of the body-muscles, and especially by the sagittal fibres 

 which extend between the coils of the uterus, and approximate the 

 two surfaces of the joint. 



Special attention must be devoted to the posterior end of the 

 uterus, which extends behind the rosette, and is formed of a coiled 

 canal, becoming ever narrower and more delicate the further it 

 extends. The upper coils appear as comparatively regularly alter- 

 nating loops (Fig. 368), but shorter and thinner than those of the 

 rosette ; inferiorly, however, the windings become more irregular in 



