566 THE MICROSCOPE. 



as together constituting the stomach ; but they are caeca], 

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

 entrance above mentioned. The water-vascular system, 

 artificially coloured in the plate, or rather the vessels thus 

 named, bear a very striking resemblance to that of arteries 

 or veins ; and the centrally-placed pouch, shown in the 

 figure, might very easily be taken to represent the heart. 

 This large cavity gives origin to two primary trunks, which 

 pass forward along the inner sides of the digestive caeca ; in 

 their passage they send off secondary branches, which divide 

 and sub-divide until we arrive at a series of minute capil- 

 lary ramifications ; the latter, according to Blanchard, 

 terminating in small oval-shaped sacs or lacunre. 



" It should be further observed, that the surface of the 

 Amphistome, though quite smooth to the naked eye, is 

 clothed with a series of minute tubercles, which may be 

 readily brought into view under a half- inch object glass. 

 Beneath the cuticle we find a layer of cellules forming the 

 true skin ; and beneath this, again, there are two, if not 

 three, layers of muscular fibre ; an anterior longitudinal 

 series and an inner circular set being readily distinguish- 

 able. The substance of the body is traversed by bands of 

 cellular parenchyma or connective tissue, which here and 

 there form thickened sheaths for the support of the various 

 delicate organs above described." The reproductive organs 

 of flukes possess the greatest amount of interest both from 

 an anatomical and physiological point of view. They are 

 produced from eggs, which are found in large numbers in 

 the ova-sac ; varying in size from l-150th to l-250th of 

 an inch, 



"'The large fluke (Fasciola hepatica) is not only of 

 frequent occurrence in all varieties of grazing cattle, but 

 has likewise been found in the horse, the ass, and also in 

 the hare and rabbit, and in some other animals. Its occur- 

 rence in man has been recorded by more than than one 

 observer ; the oral sucker forming the mouth leads to the 

 short oasophagus, which very soon divides into two primary 

 stomachal or intestinal trunks, which latter in their turn 

 give off branches and branchlets ; the whole together form- 

 ing that beautiful dendritic system of vessels which has 

 often been compared to plant-venation. This remarkably- 



