30 On Flukes. 



more or less present in the organs included under this group 

 of structures, owing particularly to the presence of multitudes 

 of minute eggs, whose shells are highly tinged. Two shades 

 will be introduced ; namely, orange yellow to characterize the 

 female tissues, and pale yellow to represent those of the oppo- 

 site sex. 



Other pigments may be occasionally employed where the 

 natural colouring of the skin, or other special circumstances, 

 seem to render their exhibition suitable. 



The fluke which we have first selected for description and 

 illustration is the cone-shaped amphistome, or Amphistoma 

 conicum of Eudolphi. This parasite is common in oxen, sheep, 

 and deer, and it has also been found in the Dorcas antelope. 

 This amphistome almost invariably takes up its abode in the 

 first stomach, or rumen, attaching itself to the walls of the 

 interior. In the full-grown state it never exceeds half an inch 

 in length ; but in the accompanying plate we have purposely 

 given a large central figure (1), representing the fluke magnified 

 ten diameters linear, whilst the upper figures (2 and 3) 

 respectively afford an anterior and lateral view of the same 

 individual. If closer inspection be made it will be seen that 

 the animal is furnished with two pores or suckers, one at either 

 extremity of the body, the lower being by far the larger of the 

 two. By means of the latter the amphistome anchors itself to 

 the papillated folds of the paunch, or first stomach, as this 

 organ is improperly called. 



In the central figure the following structures may be 

 remarked. The oral sucker at the anterior end, or head, as 

 it is termed, leads into a narrow tube forming the throat or 

 oesophagus, and this speedily divides, or rather widens out, 

 into a pair of capacious canals. These cavities are correctly 

 regarded as together constituting the stomach; but they are 

 cgecal, that is, closed below, having no other outlet than the 

 entrance above mentioned. Hence we justly infer that nearly 

 all the materials or juices received into the body of the fluke 

 are in a fit state to be at once absorbed into the system ; yet 

 it is not at all improbable that indigestible particles are occa- 

 sionally expelled from the mouth, when the ceeca are over- 

 distended by their accumulation. On examining flukes it is 

 very common to observe this engorgement of the alimentary 

 canals, and, taken in connection with other characters, it 

 affords the parasitologist a ready mode of ascertaining to what 

 gem/us tho Entozoon belongs. In most flukes the digestive 

 canal is thus simple and divided ; but in Fascioles, as we shall 

 subsequently illustrate when describing the common liver fluke, 

 it is strikingly dendritic or regularly branched. 



The water-vascular system next demands our attention. 



