292 DR. T. S. COBBOLD Olf THE L/tEGE HUMAN FLUKE. 



known that the Planarians, especially the terrestrial forms, are 

 carnivorous in their habits. In proof of this view of their habits, 

 Mr. Moseley has recently brought forward additional evidence in 

 his elaborate memoir " On the Land- Planarians of Ceylon" (Phil. 

 Trans. 1874). The significance of these facts in relation to any 

 theory of descent must not be lost sight of "Without dwelling 

 upon that point, however, I pass on to observe that our Distoma 

 crassum, both as regards the restricted charcter of tbe vitelligene 

 glands and the simple form of the testis, and also in respect of the 

 unbranched state of the digestive caeca, shows a close adherence 

 to the central Distome type, in which, as we have seen, Mr. Busk 

 originally placed it. If there be any structural departures from 

 the common type, they are connected with the testes. I believe 

 that the two organs are here merged in one large compound 

 gland. Amongst Trematodes, as Von Siebold long ago pointed 

 out, such an arrangement occasionally exists. Further observa- 

 tions are necessary to clear up this and one or tw'o other points 

 of structure which I strove in vain to make out accurately. 

 Nevertheless, fragmentary as the present data are, it is something 

 not only to have stumbled upon a second and a third instance of 

 the occurrence of this rare entozoon in the human body, but also to 

 have been enabled to confirm the truth of almost all that had been 

 previously conjectured respecting its structure, and at the same 

 time also to have acquired new facts of sufficient importance to 

 fix the affinities with precision. 



Here my paper, as regards new facts, virtually closes ; but so 

 much interest naturally attaches itself to the question of the ori- 

 gin and early stages of growth of the parasite, that I feel our time 

 will not be wasted if we take into consideration some of the more 

 important and recently ascertained facts that tend to throw light 

 upon the subject. 



At the outset I hinted that the Ningpo oysters may have played 

 the role of intermediary bearers in the case before us ; and as 

 tending in some measure to strengthen that notion, it should be 

 borne in mind that Mr. Busk's original fluke-bearer came from 

 eastern parts. It is not improbable, therefore, that the Lascar 

 may have partaken of the same species, either of fish or of shell- 

 fish, that the missionary and his wife partook of. Be that as it 

 may, the frequency of the occurrence of Trematodes and their 

 larvae in marine mollusks is well known ; though until compara- 

 tively lately it was not so well understood that the singular 

 double-tailed redia or organized germ-sac, known as Bucephahcs, 



