SPECIES OF DISTOMA. 433 



circumstances, if these organs had been preceded by nucleated cells, and 

 the cells had been transformed into booklets, neither these cells in their 

 primitive state, nor in their several stages of transformation, could have 

 escaped detection. 



" The parts next to be noticed are the suckers. Indications of these are 

 visible as soon as the booklets. They appear as four circular spaces, 

 presenting a granular aspect about the size of perfectly-formed suckers. 

 The two sets of fibres next make their appearance, the radiating and 

 circular, which have not at first the sharp outline which they afterwards 

 acquire, but still appear obscurely granular. As the tissue of these organs 

 possesses nothing characteristic like that of the parts just described, the 

 progressive changes which they undergo during the different periods of 

 their formation can be but imperfectly distinguished ; and hence no further 

 description of them will be necessary. 



" It has been observed in respect to the two sets of organs above 

 described that their size does not increase materially after once formed ; 

 exactly the reverse is the case in reference to the part called the neck, 

 and the quantity, though not the size, of the laminated bodies, which 

 increase in number as the cavity of the latter increases in size. These 

 bodies appear as soon as the hooklets and suckers, and they are as large 

 when first formed as afterwards, but there are indications of the transverse 

 wrinkles of the neck before either hooklets or suckers can be distinguished. 

 The neck afterwards continues to grow, so that its relative length in 

 respect to the ventral portion is some indication of the age of a 

 Cysticercus. 



" It is probable that this part does not arrive at its full size until after 

 it has been protruded, which I have never seen to be the case in any 

 animalcules occurring in or between the muscular fibres, and which perhaps 

 is not effected until the entozoa quit their confined locality between the 

 muscular fibres, and gain access to the free surface of a mucous membrane, 

 there, as physiologists generally believe, to be further developed into a 

 higher form of entozoon." 



Appendix B. 



On the occurrence of species of Distoma in the human body. 



In addition to the cases in which species of Distoma have oc- 

 curred in the human body, and mentioned by the author in the 

 text, the following cases will, I make no doubt, be interesting 

 to the reader. 



Dr. Budd, in the second edition of his work on ' Diseases of 

 the Liver/ gives the following case : 



"A few years ago a single fluke was discovered by my colleague (Mr 

 Partridge) in the gall-bladder of a person who died in the Middlesex Hos- 



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