336 On Parasitic Castration in Lumbiicus herculeua. 



Microscopical examination showed that the cause of the 

 abnormality lay in a bacterial infection, not only the cyto- 

 phores but the spermatocytes themselves being crowded with 

 minute splierical bacteria in active movement. The contents 

 of the seminal vesicles of some of those individuals (from the 

 same plot of ground) v^^hich possessed a clitellum were also 

 not entirely normal, a certain proportion of the sperm mother- 

 cells containing the bacteria. 



The greater number of the bacteria are spherical, measuring 

 about •0014 mm. in diameter ; others are elongated, measuring 

 •007 by ^0014 mm. Sometimes distinctly larger individuals 

 occur, measuring '0035 by '0043 mm. 



In all the infected worms tlie seminal vesicles contained 

 unusually large numbers of Monocystis — spores, cysts, and 

 free swimming individuals, but not the attached form. 



In all cases the amoebocytes were conspicuous in the 

 seminal vesicles, and were crowded with ingested and now 

 motionless individuals of the bacterium in question. In tills 

 contiexlon Brasil's remarks are interesting (i) : — " La 

 presence d'amibocytes nombreux dans les vesicules seminales 

 des Liimhricus est normale et connue. Les amibocytes 

 seraient attires dans ces organes, a-t-on dit, par les parasites 

 qui y abondent presque toujours (Gr^garines du genre Mono- 

 cystis) et contribueraient par leurs proprietes phagocytaires a 

 prdvenir un encombrement qui, s'il n'dtait entrave, about i- 

 rait fatalement h. la castration tout au moins partielle de 

 riiote." Brasil, iiowever, thinks that the amoebocytes have 

 another and more general function : — " Le role principale des 

 amibocytes des ve.siculessdminales consisterait dans le nettoy- 

 age complet de ces organes aprbs les Amissions spermatiques. 

 . . . L'action sur les parasites ne serait qu'un epitrode particu- 

 lier de cette fonction plus geudrale." 



I have never observed this asserted resorption of the repro- 

 ductive elements by the phagocytes : in those instances in 

 which I have found the seminal vesicles of the eartliworm 

 containing only amoebocytes charged with granules, as Brasil 

 describes, the condition has been brought about by the 

 bacterial destruction of the spermatic elements. 



This bacterium is probably as constant an occupant of the 

 seminal vesicles of the earthworm as is Monocystis. I have 

 ftjund it in small numbers in healthy worms obtained from 

 various places. In a healthy worm, however, the majority 

 of the bacteria are ingested by the amoebocytes and are 

 consequently motionless ; often great crowds of bacteria are 

 seen in the amoebccytes, while living individuals are only 

 found by searching. Their inconspicuousness when motion- 



