LIFE HISTORY OF THE LIVER-FLUKE. 127 



the ventral sucker it bifurcates to form the two limbs of the 

 intestine, which reach, one on each side of the ventral sucker, 

 to nearly the end of the body. The limbs of the digestive 

 tract are solid, being formed for the most part by single rows 

 of thick disc-shaped cells (fig. 13). The cells are finely 

 granular at this stage, and show out distinctly against the 

 clear spheroidal cells which surround the limbs and produce 

 concave impressions on the surface. At the sides of the body 

 refractive granules begin to collect in certain of the cells, which 

 are destined to assist in the formation of the cyst of the 

 cercaria, and may conveniently be termed cystogenous. At first 

 the granules are few and inconspicuous, but gradually become 

 more and more numerous until at length they may obscure the 

 nuclei, and render the cells opaque. Many of the cells in the 

 body of the cercaria are crowded with most remarkable rod- 

 shaped bodies closely resembling bacteria in size and shape 

 (fig. 20). They reach the length of '006 mm., and are often 

 arranged in rows side by side, whilst the long axes of nearly 

 all the rods in each cell have approximately the same direction. 

 Both Wagener and De Filippi appear to have observed similar 

 structures in the cercaria of Amphistoma subclavatum. 

 The former speaks of them as " rod-shaped corpuscles, ^^ and 

 the latter says that " their form may not inaptly be compared 

 to that of a shuttle or spindle, with thick walls, and truncated 

 at both ends. They are destined to disappear later.'^ These 

 bodies are not precisely like the narrower ones found in the 

 cercaria of the liver-fluke, but they are probably correspond- 

 ing structures.! 



An adult redia generally contains a brood numbering about 

 a score ; amongst these there will be one, two, or three cercarise 



^ Prof. Leuckart (' Zool. Anz.,' Oct. 9th, 1882) has also found these curious 

 bodies (which had already been described by me iu the ' Journ. Roy. Agric. 

 Soc.,' for April, 1881), and as he was unable to find any spines on the cuticle 

 of his cercarise, he suggests that the rod-like bodies are subsequently arranged 

 in bundles to form the spines of the adult fluke. But I have found the 

 spines iu the most mature cercarise, and can say that these rod-shaped bodies 

 have no connection with them, though I am unable to suggest any probable 

 explanation as to their nature. 



