ON AMPHILINA PARAGONOPORA 77 



In ono other case — an isolated instance — I found a s m a 1 1 

 capsule (roughly 500 microns long and 384 microns in mean 

 transverse diameter) also to contain a dozen or so degenerate 

 flat larvae and some disintegrated matter, hut in this case 

 no worm was enclosed in the capsule nor could ever have Ijeen 

 in a capsule of this small size (PI. 5, fig. 47). The only explana- 

 tion of this remarkal)le situation of the degenerate Lirvae 

 is that the larvae had been ejected from an Amphilina into 

 the l)ody-cavity of the fish (and we have seen that larvae 

 are sometimes extruded from the uterine pore long before the 

 worm escapes from the body-cavity) and that the larvae having 

 come into contact with the mesentery, a histolytic capsule had 

 been formed by the mesentery tissue to isolate and destroy 

 them (the amorphous masses are themselves surrounded by 

 capsules formed from mesentery tissue, in much the same way 

 that Linguatulid larvae become encapsuled). It will be 

 noticed from PL 5, fig. 47 that the walls of the histolytic 

 capsule are very different in construction from the walls of the 

 capsules enclosing normal amorphous bodies. 



It is thus of interest to note that larvae, if not liberated soon 

 enough, can become degenerate (1) in an active Amphilina 

 (as e.g. in the 280mm. Amphilina described above), (2) in an 

 Amphilina permanently imprisoned in its capsule, and (3) when 

 liberated into but unable to escape from the body-cavity of 

 the host (fish). The only fact which it is difficult to understand 

 is why, in the 280 mm. Amphilina, only a small proportion of 

 the eggs had developed as far as the full-grown larva stage, 

 the rest becoming degenerate while still inside their shells. 

 But perhaps this was an anomalous, as it certainly was, in 

 my observations, an isolated, occurrence : in no other instance 

 have I observed the uterus to contain anything but normally 

 developing or developed larvae. I may emphasize that the 

 flat oval type of larva seen in the 280 mm. Amphilina also 

 occurred in the capsule-imprisoned Amphilina and in the 

 histolytic capsule, and possibly this is the fully grown stage 

 of the larva, the type of larva figured by Selensky, e. g., being 

 not fully grown. 



