338 ANIMAL PAEASITES, 



between the immigration and the moment of dissection, must he 

 self evident ; however, it is also to he observed, that the deposition 

 of the lime salts depends also upon the age of the host. Thus, 

 for example, in Zenker's case, which was also investigated by 

 me, the cysts were firm, but in general very transparent, the 

 patient was of middle age ; in Luschka' s case all were calcified, 

 the patient being about eighty years old. But if once the cal- 

 careous deposition referred to has taken place towards the walls 

 of the cysts, no transparency can be produced either by solution 

 of potash or acetic acid, nor any change by boiling with ether, 

 or keeping in that fluid. The addition of concentrated muriatic 

 acid, however, appears to reestablish the solubility of the carbo- 

 nate of lime by the destruction of the organic compounds, as, 

 after the application of this, abundant air-bladders are evolved, 

 and even the darkest cysts become clear and transparent, and 

 allow the worm to be perceived in their interior. 



According to Luschka the cyst of Trichina exhibits two 

 layers, different both in their composition and signification. 

 "The outer layer, which especially determines the form of 

 the cyst, where peculiar processes exist, forms these as solid pro- 

 longations, into which the inner envelope is rarely continued and 

 only in cases of great dilatation. The tissue consists of irregu- 

 larly arranged, very fine fibres, which, crossing each other re- 

 peatedly, form a narrow-meshed net, and behave towards caustic 

 potash and acetic acid like ligamentous tissue, except that the 

 fibres do not entirely disappear, but offer a partial resistance." 

 The last circumstance was referred by Luschka, in 1851, to the 

 age of the particular fibres ; but according to his more recent, 

 admirable investigations, we see in this reaction a proof that in 

 this case we have to do with the same fundamental formative 

 material, which we also meet with in the cysts of the Cestoidea, 

 that is to say, "protoplastic fibres of the cellular tissue," to 

 which Luschka, before he was aware of their mode of produc- 

 tion and nature, had given the name of serous fibres, and to 

 which I also, following Luschka, gave the same name, in my 

 book upon " the Cestoidea in general and those of man in par- 

 ticular." A true lamellar structure cannot be recognised in this 

 layer, although it can be broken up into separate band-like struc- 

 tures. In older cysts it is difficult, in young ones easy, to bring 

 the inner layer into view, after tearing the outer one. The 

 outer envelope is at the same time the bearer of a very distinct 



