FERTILIZATION IN THE PARASITIC COPEPOD, 

 LERN^OPODA EDWARDSII OLSSON. 1 



NATHAN FASTEN. 



CONTENTS. 



General Remarks 115 



The Male Reproductive Organs 116 



The Female Reproductive Organs 117 



Fertilization 1 18 



Summary 119 



Bibliography 120 



GENERAL REMARKS. 



Wright (1882), in discussing reproduction in the parasitic 

 copepod Achtheres micropropteri deprecates the fact that so little 

 is known of the exact method of fertilization in the parasitic 

 copepods, and adds that "a thorough examination of the male 

 reproductive apparatus of the Lerneopodidae is very desirable 

 for the purpose of elucidating the formation of the spermato- 

 phores in the parasitic Copepoda." Since Wright's work no 

 one has published any results along this line. It, therefore, 

 seemed advisable to investigate this problem a little more fully. 



The following studies were made on the parasitic copepod 

 Lerntzopoda edivardsii Olsson which infests the gills of the brook 

 trout Salvelinus fontinalis. The writer, while in the service of 

 the Wisconsin Fish Commission, during the summer of 1912, 

 secured a lot of fine stages of this organism in copulation, from 

 the time the male attaches itself to the female until the actual 

 fixation of the spermatophores near the genital pores of the 

 female's body. Many mature males and females were also 

 secured. 



The material was fixed in a 5 per cent, solution of corrosive- 

 acetic for eighteen hours and was then washed in running water 

 for a day. Selected stages were stained in toto in borax- 

 carmine for thirty-six hours, and the excess of stain was removed 

 in water or in very weak acid-alcohol. The material was next 



1 From the Zoological Laboratories, University of Wisconsin. 



