DISTOMA HEPATICUM. 249 



cup. In young Distoma which are still immature, I have always 

 found it, and generally diffused over the sides of the whole body. 



With regard to the parenchyma of the Distoma, Aubert says, 

 " The parenchyma, which is rendered more finely granulated, 

 darker, and more brittle by acids, and very slowly dissolved by 

 alkalies, and which probably consists of two substances a gra- 

 nular mass (perhaps analogous to the stearine tablets of the 

 Infusoria), and a transparent, homogeneous mass (sarcode) con- 

 taining these granules is tough, and slowly extensible and con- 

 tractile in all directions, so that from the want of direction in its 

 structure it exhibits contractility in all directions." 



The consistence of the parenchyma of D. hepaticum also 

 very closely resembles that above described. A variation prevails 

 here only in regard to the muscular fibres, which is of the more 

 importance, as by this means a circumstance may be explained 

 which has given origin to several different interpretations. 



If a fragment of the parenchyma of a Distoma be moistened 

 with a little dilute sulphuric acid, and the latter be allowed to 

 act only until the edges of the preparation have become white 

 and opaque, and the preparation be then washed quickly with a 

 little water, the following clearly distinguishable muscular layers 

 are perceived : 



1. A layer of longitudinal fibres, running straight and not 

 very strong. 



2. A layer of very thick and long transverse fibres, but little 

 twisted. 



3. A layer of short, often fusiform, thick transverse fibres, 

 often very strongly bent into an S-form, and 



4. A layer of short, thick fibres, uniting into an obtuse cone, 

 placed at more or less regular intervals, and inserted between the 

 previous layers rather in an oblique or perpendicular direction. 

 This layer is particularly remarkable for the change which it 

 undergoes in water. Thus, if we examine individuals kept in 

 water, these obtusely conical bundles of fibres have disappeared, 

 and we find in place of them small quadrangular structures, very 

 obtuse towards the apex, on which an extremely fine striation 

 is now to be observed. The same structures are also detected 

 after the treatment of such individuals, preserved in water, with 

 dilute sulphuric acid ; but a similar appearance is never observed 

 in animals which have been taken directly out of the gall- ducts, 

 and examined without any preliminary treatment with water. 



