516 JOSEPH STAFFORD, 



curved course, if they are formed only by the neighboring cell naem- 

 branes, that is if they are only chinks between the cells or inter- 

 cellular spaces. 



The distribution of the funnel organs may be already surmised 

 from the number and character of the excretory vessels. They occur 

 in the parenchyma of all parts of the animal, excepting ventral sucker, 

 penis-sack and pharynx, but in greatest numbers in the region of the 

 peripheral muscle layers, along the septum, just outside the penis-sack 

 and round the margins of the ventral sucker immediately above the 

 limiting membrane. The presence of this membrane can have no 

 effect in determining their absence below it, for larger and smaller 

 vessels pass through the diaphragm. The only limiting means is no 

 doubt the dense structure of the sucker itself, and a like statement 

 may be made regarding the pharynx and penis-sack. 



A consideration of the number and distribution of the funnel 

 organs suggested to me, as in other Trematodes it has been suggested 

 to others, the question whether the funnel organs are not the real 

 excretory organs and the branching canal system only the necessary 

 conducting apparatus. The localization of the funnels in the regions 

 QÎ most active metabolic changes might seem also to strengthen this 

 view. But at the same time we must remember that the funnels 

 necessitate a like distribution of the capillaries, which touch a greater 

 number of cells and, on account of their extremely thin walls, doubt- 

 less permit easy osmotic transmission of excretion fluids. 



ReproductÎYe system. 



The reproductive organs (Fig. 16) of Aspidogaster are distributed 

 in both upper and lower portions of the body and occupy the greater 

 part of the space not taken up by the intestine. Of the two sets of 

 organs — male and female, in the same individual — by far the 

 greater space is required for all those parts associated with the pro- 

 duction of the primitive ova, the supply of food material for the 

 growing embryo, the formation of a protecting shell, and the retention 

 of the whole in the body of the i)arent, under a suitable developing 

 temperature, until the young miracidium is completely formed. 



The essential elements of the male system — the spermatozoa 

 — make their way from the testis, approximately in the centre 

 of the ventral half of the animal, in a fairly direct course through 

 vas deferens, vesicula seminalis and penis, to the genital 

 sinus. The primary elements of the female system — the ova — 



