96 Mr. E. Ray Laiikester on the Organization 



penis, &c., with its expanded trumpet-like orifice opening in 

 the ninth segment, totally devoid of spermatozoa, though 

 working its cilia actively. The fact that a male and a female 

 organ in the ninth segment were aborted, and a male and a 

 female organ normally developed in the tenth, shows that 

 there is no "solidarity" between the female organs as such, 

 but that their development or abortion is due simply to the 

 greater or less nuti-ition of their particular segment. These 

 specimens were females in the essential, male in the accessory 

 organs of generation. 



Dr. Fritz Ratzel has recently given reasons for regarding 

 Tuhifex as exhibiting a dimorphism of the ovaries, the ova 

 being usually detached as they develope from the terminal 

 portion of the ovary which hangs in the tenth fasciculate seg- 

 ment in close contact with the glandular dilatation of the male 

 efferent duct, whilst in other specimens floating masses of large 

 ova arefound freely in the body-cavity. I have observed the fact 

 seen by Ratzel, but do not think it requires his interpretation. 

 Tuhifex occurs in the Thames in the sexual condition in 

 winter and summer. In the autumn large specimens devoid 

 of genital organs are to be found. In specimens taken in the 

 summer I have sometimes seen a very curious condition of the 

 ovary, masses of large ova being detached instead of one much 

 larger ovum alone. I think, from the a])pearance of the sub- 

 stance of the ova and the condition of the copulatory organs, 

 that this is an abortive development, ending in the degenera- 

 tion of the ovaries, both they and the testicular elements be- 

 coming, after a certain season of activity, absorbed in the peri- 

 visceral fluid. I have also found curious corjniscles, evidently 

 aborted sperm-cells, in the perivisceral cavity of Tuhifex in 

 the autumn. 



The structure and position of the testis appear not to 

 have been fully made out by M. Clapar^de or by other 

 writers ; and this is true not only of Tuhifex, but of the 

 other Oligochaita. Leydig's figure of the young testis in 

 Phreoryctes Menckianus (Max Schultze's Arcliiv, vol. i.) is 

 the only one which agrees with what I have seen. I have 

 already figured the developing testis in GhaHogaster (Quart. 

 Journ. of Micr. Science, 1869); those of the other Oligochteta 

 do not much differ from it. By examining very young speci- 

 mens of Tuhifex or Limnodrilus, the real nature and origin of 

 the sacculate masses of zoosperms seen in adults may be 

 ascertained. The young Tuhifex of a quarter of an inch in 

 length presents in the ninth fasciculate segment a pair of pyri- 

 form protoplasmic masses, very small, hanging one on either 

 side of the nerve-cord ; an exactly similar pair is seen in the 



