NATHAN FASTEN 



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in the chalimus larya of the Caligidae, we can infer what occurs 

 here. Th outer end of the attachment filament is enlarged 

 into the mushroom form already described, and is filled with 

 adhesive fluid. It lies just inside the frontal margin, covered 

 only by a very thin outer cuticle. Doubtless, the larva rubs 

 its frontal margin against the skin of the gill arch of its host 

 and in' this way burrows through the slime and outer integu- 

 ment to the solid tissue underneath, holding on meanwhile 

 with its powerful maxillipeds. At the same time the thin 

 covering of the frontal margin of the parasite is broken through 

 and the end of the filament is brought in contact with the gill 

 h, to which it adheres firmly. By moving away from the 

 point of attachment the coiled filament is drawn out of the 

 bodv of the larva. As it comes forth the larva grasps it between 

 the claws at the tip of the second maxillae." 



This process of attachment as surmised by Wilson, however, 

 was not found to be the method by which Lernaeopoda edwardsii 

 attaches itself to the gills of the brook trout. By the aid of 

 the microscope I observed the process of attachment four times. 

 As soon as the copepod comes in contact with the filament of 

 the gill, its mouth parts are inserted into the flesh, and by means 

 of the powerful claw-like second maxillae it begins to rasp the 

 filament until it forms a cavity within it. As soon as this occurs, 

 the anterior portion of the copepod's head, the frontal margin, 

 is brought in contact with the cavity and the enclosed attach- 

 ment filament is injected into the hole. The spherical mush- 

 room body adheres to the flesh and the regenerating tissue of 

 the gill soon encloses it tightly, thereby fastening the organism 

 firmly. The mouth parts are then withdrawn from the flesh of 

 the gill filament. In this condition the parasite remains attached 

 for a short time. Then the second maxillae detach the posterior 

 region of the attachment filament from the head margin and 

 they themselves become permanently attached to this end of 

 the filament. Degeneration soon sets in and the organism 

 changes considerably. The female copepod remains thus attached 

 throughout life, while the male remains attached in this way 

 until shortly before it is mature for copulation. 



Wilson believes that the transference of the filament from the 

 frontal margin to the tips of the second maxillae takes place 

 at the time of fixation to the host, and that the larvae are never 



