THE PROCESS OF EGG-MAKING IN A TREMATODE. 



EDWIN LINTON. 



An outline of the process here described was pubHshed by me 

 in connection with the description of the species Epibdella Imm- 

 pusii, an ecto-parasite of the sting ray {Dasyatis centrurd)} 



Since opportunities of witnessing this instructive phenomenon 

 are rare, and descriptions are wanting, even in the larger text- 

 books, and, further, since the knowledge of the process has proved 

 to be of great value in explaining to students the anatomy of the 

 reproductive apparatus of the trematodes, I venture to publish a 

 description of the process as I have seen it. 



Every teacher of zoology is familiar with the anatomy of some 

 typical trematode. The description of the relations of the various 

 parts of the complicated reproductive machinery is about as far 

 as one is apt to go in lecturing to a class, unless he has happened 

 to see the machinery in operation, or, possibly, has had access 

 to a description of the physiological working of that machinery. 

 If what I have here written will help to vivify now and then a 

 lecture on the reproductive apparatus of the trematodes I shall be 

 repaid for the small trouble it has been to write out this narrative. 

 The species E. buuipusii is peculiarly well adapted for the 

 study of the process of egg-making. The animal is small enough 

 to allow of satisfactory study with low magnification, and is, 

 withal, transparent enough to permit rather minute details to be 

 clearly seen. Furthermore, the animal can be kept for several 

 hours in sea water under slight pressure without impeding the 

 normal action of the reproductive organs. 



Anatomy. 



In this description only the anatomy of the reproductive 

 organs is considered. Reference to the figures and the explanation 

 of the same will be necessary in order to follow this description. 



As in most trematodes the individuals in this species are her- 



Bulletin U. S. Fish Commission for 1899, PP- 286-7, ''gs. II-15. 



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