188 ENTOZOA. 



been solved if the calculi had been broken up, in order to ascertain 

 their structure. It is just possible that dead distomes may have 

 formed their nuclei, and if so, the circumstance would, of course, 

 point to the worms as the original source of the malady. 



Into the minute anatomy of this trematode it is unnecessary to 

 enter at any length, because, in the main, its structure corresponds 

 with that of Fasciola, although great differences obtain in respect of 

 the form and disposition of the internal organs. These have been 

 partly indicated already, but there are still some points worthy of 

 consideration. Thus, in connection with the digestive system, 

 Walter has described a special set of salivary organs. Leuckart, 

 who appears to attribute to them an independent function, says 

 that they are readily visible in the living animal. " They are found 

 in rather considerable numbers, scattered over the front part 

 of the body, and appear in the form of large granular cells 

 (measuring ^q), enclosing a globular nucleus, and each of 

 them terminating in a thin and long filiform excretory duct. All 

 the ducts are directed forwards towards the oral sucker, into which, 

 according to Walter's description, they open in a partly isolated, 

 and partly combined manner." In other particulars the digestive 

 apparatus is simple, the mouth and muscular pharynx being fol- 

 lowed by a narrow oesophagus, which divides into two blind intes- 

 tinal tubes, which become very gradually widened as they approach 

 their inferior limits. 



As regards the nervous system, the only distinction worth 

 noticing consists in the more backward position of the commisural 

 filament, which connects the two cephahc ganglia ; and even here, 

 according to Leuckart, considerable variation occurs. The excre- 

 tory system is well developed, and terminates inferiorly in a very 

 conspicuous sac, which latter is usually filled with active molecular 

 particles, and appears to be capable of extrusion. The repro- 

 ductive organs are, for the most part, easily made out ; but except 

 as regards the lobulated and simple form of the testes, the greater 

 number and altered position of the uterine folds, and the very 



