HYDATIDS. 161 



it is furnished with four suckers and a proboscis, and 

 encircled by a double festoon of hooks, the number of 

 which, according to Kuchenmeister, amounts to from 

 28 to 30 or from 46 to 52. The head of the animal is 

 separated from its body by a groove, and on its pos- 

 terior extremity is a transverse cleft or depression, in 

 which is inserted a cord-like appendage, by means of 

 which the creature maintains its seat upon the vesicle. 

 The body presents elongated strise, and between these 

 strise are seen oval lime-like corpuscles, resembling those 

 found upon the cysticercus. In its developed condition 

 the creature appears in the above form ; but this is not 

 always the case, as other forms are observed, where 

 the mother-sac contains no daughter-vesicles, and the 

 scolices only grow upon the inner surfaces of the pri- 

 mary sac. Other hydatids are met with which contain 

 no scolices at all ; here the external capsules is lined 

 by a mother-sac composed of several layers in which no 

 scolex can be detected, either on its surface or in the 

 fluid within : in form they may assume the shape of a 

 heart, a pitcher, or a horseshoe. 



CHEMICALLY, the fluid filling the vesicles is colour- 

 less, clear, or slightly opalescent, of low specific gravity, 

 viz., from 1*008 to 1*015. It coagulates readily by heat or 

 Nit. acid, and contains a very small amount of fat. A 

 thousand parts will yield fifteen parts of solid ingre- 

 dients, principally common salt, a trace of sulphate of 

 soda, phosphate of lime, and some albuminous extrac- 

 tive matter. The envelopes of the hydatids leave when 

 dried a brown residuum which dissolves with a deep 

 brown colour when boiled with hydrochloric acid. 



Hydatids are formed in all parts of the liver ; in the 

 M 



