Mary Vincent 
303 
A section through a newly-formed cyst shows the protomerite and deuto- 
merite of the sporonts still distinct (Fig. 4 D): at a later stage the septa 
disappear (Fig. 4 E). 
Several abnormal cysts were observed in which three sporonts had encysted 
together; this, however, was quite exceptional. In this connection it is inter¬ 
esting to note that Laveran and Mesnil (1902) found that the encystment of the 
sporonts of Pyxinia frenzeli takes place by two or by three with equal frequency. 
E 
Fig. 5. A, young cyst from intestine, x 400. B, a later stage. C, ripe cyst. D, a ripe cyst much 
contracted discharging its spores. E, spores, x 667. 
The cysts of Pyxinia anobii seen in the intestine are spherical, sometimes 
slightly ellipsoidal, and measure between 70 y, and 90p, in diameter. The cysts 
were present in great numbers in the excreta of the larvae, and the whole 
process of spore formation takes place outside the body of the host. After 
evacuation of the cyst the protoplasm which is to give rise to the gametes, 
and subsequently to the sporoblasts and spores, shrinks towards the centre, 
and the cyst wall becomes much thicker. The envelope enclosing the cyst 
consists of two portions: an outer epicyst, and an inner endocyst. When ripe 
the spores escape by the rupture of the two integuments: no traces of sporo- 
ducts were observed. 
20—2 
