274 ANIMAL PAEASITES. 



regarded as young individuals of that species. I shall speak a 

 word as to the necessity for the separation of the two animals. 

 Whoever compares the annexed figures, and also takes the 

 trouble to examine young D. hepaticum of about the same size 

 as D. lanceolatum, will be convinced that Schaeffer, Rudolphi 

 in his earlier works, and Mehlis were right in establishing two dis- 

 tinct species, and that Goeze, Bloch, Zeder, Bremser, and Rudolphi 

 at a later period, were quite in the wrong in regarding D. lan- 

 ceolatum as a young D. hepaticum. 



As to the structure of the separate parts of the Distoma, 

 there is still the following to be said. The buccal sucker is 

 much larger in proportion than that of D. hepaticum. Ac- 

 cording to Walter (Siebold and Kolliker's ' Zeitschr./ viii), the 

 long, tortuous efferent ducts of peculiar glands, which are some- 

 times isolated, sometimes united, permeate the buccal sucker on 

 its outer wall, and open in this way in its innermost wall. These 

 efferent ducts, which carrv the finelv granular contents of the 

 glands towards the buccal sucker, with distinctly visible lively 

 movements, serve as the efferent canals of the glands which act 

 as salivary organs. The pharynx, which in D. hepaticum forms 

 a sort of cup in very good proportion to the size of the buccal 

 sucker, is very small and globular in D. lanceolatum. The 

 round pharynx is followed by a short common oesophagus, and at 

 the level of the apex of the sac of the penis there commences a 

 bifurcation of this intestinal canal, which runs simply and without 

 any ramifications on each side at the sides of the uterus, nearly 

 to the hinder extremity of the latter, where it terminates in a 

 csecal and somewhat clavate end. Its contents are a dark, 

 finely granular, molecular mass. As nutriment, this parasite 

 makes use of the bile from the finer gall-ducts, but also, perhaps, 

 the blood which circulates in the walls of those vessels, as I have 

 seen most of the gall-ducts inhabited by this Distomum filled 

 with thinly fluid contents of a blood-red colour. 



The testicles lie one behind the other, and in the anterior part 

 of the animal, immediatelv behind the ventral sucker. Thev are 

 lobed by lateral indentations; the anterior one is smaller than 

 the posterior, and each has a funiculus spermaticus which opens 

 anteriorly into the penis-sac. Immediately behind the larger 

 posterior testicle, and about at the level of the point of union of 

 the yelk-sacs, lies a very small retort-shaped body, bent back- 

 wards, with an efferent duct opening posteriorly, which appears 



