D1STOMA HEPATICUM. 255 



layers of eggs closer in the interior of the canal, whilst the 

 colour of the egg-shells themselves constantly becomes darker 

 and yellower, and their contents less uneven and granular. 

 I have never yet succeeded, however, either in D. hepaticum 

 or in the Bothriocephali, in recognising the exact form of an 

 embryo, or been able to free it by pressure or breaking the eggs. 

 The difference in the colour of the eggs, in different convolutions of 

 the uterus, causes the colour of the uterus itself to be different 

 also. The last convolutions situated posteriorly are white and 

 clear, the anterior ones dark yellowish. 



e. The vagina is a tortuous and rather narrow canal, just wide 

 enough to allow of the passage of an egg moving in the direction 

 of its longitudinal axis. It runs at the margin of the ventral 

 sucker, and beneath and behind it to the place where the penis 

 protrudes from the skin, where it is enlarged in the form of a 

 funnel. Here it has a common opening with the penis. It is 

 hardly possible, or very difficult, to exhibit this part in the living 

 D. hepaticum ; but the arrangement of the parts here described 

 may be very easily seen by pouring boiling water over a living 

 Distomum and scalding it, and then crushing the animal com- 

 pletely, but slowly, between two glass plates. 



2. Male sexual organs. a. Testicles. The two testicles (ante- 

 rior and posterior) differ entirely in our Distomum from those of 

 most other Distoma, and as the only object has been to find the 

 ordinary conditions again, a great number of mistakes have been 

 published, but the true state of matters has long been overlooked. 

 The testicles of Distoma are neither oval nor round, but they 

 are amongst the multifariously lobed and notched testicles, and 

 from their nature they must come nearest to the testicles of 

 Amphistomum subtriquetrum giganteum and Distomum hians, which 

 in consequence of a number of very deep incisions, form a tuft 

 of blind canals. Thus, in the middle of the whole hinder two 

 thirds of the animal, we see a complication of repeatedly en- 

 twined, csecal, intestinal convolutions, reaching immediately to the 

 inner borders of the lateral yelk-sacs, and ceasing pretty exactly at 

 the above-mentioned part of the latter. Hence it happens, that 

 these structures may be taken almost uninjured out of the 

 body, when we cut away, with a fine knife, the lateral margins 

 of the animal as far as the yelk-sacs extend inwards. In front, 

 from the ventral sucker, this organ extends in a pair of small, 

 lateral shoots, which, to choose a readily accessible figure for 



