280 ANIMAL PAEASITES. 



tines and bladder ; part of them were opaque, and filled with yelk- 

 mass ; in part the embryo shone through the yelk-mass, which 

 was for the most part absorbed ; and part of them contained, 

 together with a few yelk-corpuscles, mature embryos contracted 

 into a globular form, or extended and elongated, moving in every 

 direction, or even in the act of bursting the egg-shell. In 

 the latter case they extended themselves in length, and with a 

 strong jerk ruptured the egg-shell towards the side, which always 

 took place with a longitudinal slit under the inspection of Bilharz, 

 although he also met with egg-shells which were slit transversely 

 and obliquely. The vitelline membrane was torn at the same 

 time, and the little animal escaping, according to Bilharz, 

 with its hinder end first, began to work slowly with its ciliary 

 coat, and endeavoured to free itself from the egg by lively move- 

 ments in all directions, which often occupied a considerable time. 

 The little animal, after its escape, had a longish cylindrical form, 

 thicker in front and obliquely conical behind ; at the anterior end 

 was a proboscidiform projection, with a sucker-like impression, 

 and over the whole body a ciliary coat, by the aid of which it 

 moved, revolving in the water, and alternately extending and con- 

 tracting itself. Through mucus, egg-masses, &c., it crept in the 

 manner of a worm. In the anterior end of the body two pyriform 

 corpuscles were seen lying close together, from each of which a 

 thin stalk ran to the proboscis ; in the hinder part were numerous, 

 small, globular bodies. No reception of nourishment took place. 

 After remaining for about an hour in water, the animal ac- 

 quired superficial vesicular (mulberry-shaped) projections, lost 

 its power of motion, and became dissolved. 



The next step in development was seen by Bilharz in 1851, 

 but not further comprehended or indicated. The best de- 

 scription and figure is due to Griesinger, whose memoirs I 

 make use of here, arid on which I shall also depend in the patho- 

 logical portion. 



The further development of the above-mentioned, infusorial 

 embryos, is as follows : 



Griesinger and Bilharz often found, in the midst of the cal- 

 cified eggs which had allowed their embryos to escape ( egg- 

 shells), deposited in various parts of the liver and of the mucous 

 membranes, peculiar, husk-like, doubly compressed, or round, 

 bi-convex, sharp-edged, lougish, brownish-yellow bodies, furnished 

 with a toothed excrescence, which were of the same size as the 



