THE CVSTIC ENTOZOA. 497 



might be entozoa (having been led to make just the converse 

 of your conjecturo), but Mr. Marshall, formerly of our mu- 

 seum, having examined these ' Pacinian ' bodies two or three 

 years ago (quite independently of any suggestion from me), 

 I found nothing to confirm this conjecture on his showing me 

 their structure. I have since seen llenle and Kolliker's me- 

 moir, which includes the substance of Pacini's observations. 



" Rudolphi, as far as I know, never examined the structure 

 of the spheroidal bodies of Monro ; and the only notice of 

 them which I have met with in his writings (to which he did 

 not refer me) is in his Hisforia Katuralis Entozoanim, vol. ii. 

 part ii. page 277, when, under the head of 'Dubious Entozoa,' 

 he enumerates an object described and figured by Pathke, 

 under the name of ' Hydatula Gadorum,' which that obser\'er 

 found in the jn'a mater of the Gadiis morrhua and G. virens, 

 often in great numbers, and which appeared to be a vesicle 

 containing a worm. The nature of the parasite was doubtful, 

 but supposed in some degree to resemble that of a Cysticercus, 

 and hence the name applied to it by Pathke, but Pudolphi 

 denies that it is a Cysticercus, though he does not know to 

 what genus to refer it, he adds * an Cucullanus?'" 



This entozoon, as stated by ^lonro, is found in great num- 

 bers in the gelatinous substance which surrounds the brain, 

 spinal cord, and semicircular canals, in the cod, haddock, and 

 whiting. They are also very numerous in the larger branches 

 of the nerves, and particularly on those of the pectoral and 

 caudal fins. In the former situation they are suspended in 

 the gelatinous fluid by fibres of areolar texture and by blood- 

 vessels ; in the latter they lie embedded in the substance of 

 the nerve, the ultimate fibres of which are spread in bundles 

 over the surface of the cysts. 



The cysts are produced spheroids, somewhat flattened ; 

 their long axis measures about one-fourth of a line. 



They consist of three tunics ; an external, which appears 



2 K 



