LIFE HISTORY OF THE LIVER-FLUKE. 107 



Fasciola hepatica is reported from Australia, and a similar 

 assertion has been published in the * Veterinarian.' According 

 to Huttonl and Wallace,^ the genus Limnseus does not exisi 

 in Australia, Hence if both these statements are correct there 

 must be another intermediate host. The liver-fluke is also 

 found in North America, where the genus Limn seas occurs 

 indeed, but not the species L. truncatulus. Sheep-rot is 

 also found in the Shetland Islands, where, according to Forbes,^ 

 the genus Limnaeus is represented by the species L. pereger 

 alone. It is, however, quite possible that in the last case L. 

 truncatulus has been overlooked on account of its minute 

 size. 



III. Life-History. 



A. First generation — 1. Egg. — The eggs of the liver- 

 fluke occur in very large numbers in the contents of the bile 

 ducts and gall-bladder of the infected animal. They give a dark 

 brown colour and sandy appearance to the bile, and in some of 

 the smaller terminal ducts often form a stiff" brown mass, com- 

 pletely plugging up the lumen. They pass with the bile into 

 the intestines, and may be found abundantly in the droppings 

 of animals suff'ering from liver-rot. 



The egg is an oval body, with a smooth, transparent, 

 yellowish-brown chitinous shell. The average size may be 

 said to be O'lS mm. in length by 0*08 mm. in breadth, but 

 the dimensions vary greatly, the length from 0*105 to 0-145 

 mm., and the breadth from 0-066 to 0-09 mm. The ante- 

 rior end is a little more rounded than the posterior, and a 

 slightly serrated line running around it marks off" a circular 

 segment, forming an opercvilum 0-028 mm. in diameter. 

 The opposite end is frequently a little thicker, and slightly 

 roughened. 



The number of eggs produced by a single fluke is 



*' Transactions ' of the New Zealand Institute, vol. v, p. 18. 

 * ' Geographical Distribution of Animals,' vol. i. 

 3 ' Brit. Ass. Reijort,' 1859, p. 127. 



