238 DISCOVERY REPORTS 



The chloragogen cells become greatly elongated, more than loo/x high, and vacuo- 

 lated, the vacuoles constituting the greater part of the cell, and arranged either in a 

 single series along its length or in more than one series. 



In the spermathecae the epithelium is shed as a still more or less connected layer, the 

 wall of the organ being reduced to a thin membrane. 



In the final stages of degeneration the external annulation is lost, and in the worms 

 cleared for microscopic examination no internal structure is visible, except that some- 

 times the alimentary canal is still distinguishable, with some of the ova, and traces of 

 the spermathecae. 



Among the specimens of Marionina georgiana, the only one which was fully mature 

 was not degenerate, and was well preserved in every way. Another example, only in the 

 early stage of sexual maturity, with none of the sexual organs fully formed, showed 

 changes in the alimentary canal — the intestinal epithelium behind the clitellum was 

 loosening itself from the substratum and beginning to disintegrate ; in the body-wall the 

 muscular layer had for the most part become homogeneous and waxy-looking; and a 

 dense fibrous coagulum was seen in places in the body-cavity, applied to the chloragogen 

 layer of the gut. 



In the specimens of Michaelsena monochaeta I found the genital segments and those 

 behind them in a curious condition. There was little free space in the segments, which 

 were filled by a mass of cells and cell degenerations, but with no free spermatozoa or 

 stainable male cells at any stage, and no ova ; this filling out with degenerating masses was 

 continued backwards to segment 20, beyond which my sections did not go. In a specimen 

 in which this condition was carried to an extreme, it was noted that the alimentary canal 

 was not much altered, the heavy ciliation of the lining epithelium being preserved. 



The single example of the genus Achaeta was much disorganized internally ; both the 

 alimentary canal and the interior of the genital segments were in a very degenerate state. 



The appearances described above do not seem to be due to bad fixation ; the specimens 

 of Lumbricillus maximus, in which degeneration is most frequent, have been fixed with 

 great care, so as to preserve them in an extended condition, which naturally greatly 

 facilitates examination and sectioning ; indeed the same holds for most of the worms in 

 the collection. Speaking generally, even if small worms such as these Enchytraeids were 

 merely thrown promiscuously into spirit, we should get sections which were perfectly 

 usable for morphological purposes (though the worms would doubtless be very incon- 

 veniently bent and twisted). Moreover, some specimens of a batch may be degenerate, 

 others not so (e.g. in the case of Marionina georgiana). The only supposition by which 

 bad fixation could be held responsible for the appearances would be that the worms were 

 already dead and beginning to disintegrate before being taken for fixation ; but this I am 

 sure we can exclude. 



I have previously recorded (1926) a not very dissimilar degenerative phenomenon in 

 Enchytraeids, and curiously, there also in worms from a frigid region — Arctic, however, 

 not Antarctic (Spitsbergen). In them I frequently found a wholesale degeneration and 

 shedding of the alimentary epithelium, sometimes with overgrowth of the chloragogen 



