DISTOMA HEPATICUM. 2G7 



ment of the secondary, chlorotic symptoms by the salt of lime. 

 Another experiment was made in the same sheep-fold by lining 

 the troughs with lamp-black. The result was unsatisfactory. 



Lastly, upon my recommendation, the principal remedy of 

 Durand's mixture, turpentine, was administered to several sheep, 

 and followed by a purgative. The result of the remedy, which 

 has long been in high esteem amongst sheep-breeders, upon the 

 sheep set apart for the experiment, was still unsatisfactory, pro- 

 bably because the quantity of castor oil administered as an 

 aperient was too small. We have not given up the further prose- 

 cution of the affair, and if anything useful should be discovered 

 by us, we shall not omit to report upon it subsequently. 



Bremser put the greatest reliance in Chabert's oil, a remedy 

 which has passed gradually out of use in the present day, on 

 account of its dangerous qualities. 



The most important thing to obtain would be a rational 

 prophylaxis, founded upon the developmental history and mode of 

 life of these Distoma. As we are here acquainted only with 

 general outlines, and our knowledge of the details with regard 

 to the different species is still deficient, we will first of all give a 

 brief summary of the general subject according to Steenstrup, 

 De Filippi, G. Wagener, &c. 



From the eggs of the Distoma, which usually escape externally, 

 there issues either an infusorial ciliated embryo, which swims 

 about for a time and becomes converted by a change of skin 

 into a nurse (grand-nurse, Steenstrup), or, according to G. 

 Wagener's investigations, the nurse (grand-nurse) itself. These 

 nurses (grand -nurses, Steenstrup) are often completely organized 

 animals (Redia, De Filippi), possessing a mouth, an intes- 

 tine resembling a csecal tube, and a single or double opening 

 for the exclusion of the young, or they are simple, oval, or 

 elongated sacs without any traces of internal organization and 

 without motion (the G f 6rcn#-sacs of the older writers). In the 

 interior of these Redice or Cercaria-sa.es, but not by external 

 gemmation, the young Trematoda are now produced from the 

 germ-granules existing there ; these are rarely destitute of a tail 

 (for example, Distomum holostomum, Von Siebold), usually possess 

 a tail-like caudal appendage, sometimes cleft, which enables them 

 to swim about in the water, but which they lose on immigration. 

 The Trematoda, which are furnished with a tail (Cercaria), must 

 first pass through a multifarious metamorphosis ; penetrating from 



