Intestinal Parasites of the Dog. 307 



must be made Yi inch in front of the occipital crest and the point of 

 the instrument must be directed through the membraneous tentor- 

 ium but sufficiently low to avoid the transverse sinus. The 

 trephine usually employed has a solid pointed end like a triangu- 

 lar pyramid with sharp cutting margins, and with a screw on the 

 shaft, on which works a disc-shaped shield to prevent the instru- 

 ment from plunging into the brain when the bone has been per- 

 forated. The skin must be rendered aseptic, as nearlj- as possible, 

 and then with a boiled or flamed knife an incision is made, the 

 scalp and periosteum are dissected back, and the trephine applied. 

 Then the hydatid is perforated and withdrawn with the aid of 

 cannula^ trochar, and forceps as in the other case. 



Taenia Echinococcus (Sieb. ) A tapeworm of barely more 

 than y^ inch in length, and consisting of 4 segments only includ- 

 ing that of the head. As the fourth segment ripens it is promptly 

 detached, leaving for the moment but three segments, all imma- 

 ture. The globular head has four suckers and a pointed pro- 

 boscis bearing a double row of 28 to 50 hooks, remarkable for the 

 great size of the guard or median process. The ripe caudal seg- 

 ment is about y^ of the entire length of the worm. The eggs are 

 ovoid, 32 ju. by 25 ju, or slightly over. There may be 5,000 in a 

 ripe segment. 



The worm is easily overlooked in the colored contents of the 

 bowel, but close observation will detect the minute yellow fila- 

 ments, which become more visible when the liquid is cleared up 

 by addition of water. 



The habitat is in the small intestine of dog and wolf. 



In some districts (Iceland, Abyssinia) they are often present 

 in large numbers (1000 to 2000, Roll, Gervais) in a single dog, 

 and cause digestive disorder with convulsions or delirium. The 

 condition is distinguished from rabies by the absence of any mis- 

 chievous propensity and of paralysis, and by the presence in the 

 faeces of the ripe segments or of entire taeniae. In Iceland 28 per 

 cent, of the dogs had this tapeworm and 10,000 of the people 

 suffered from the echinococcus, which the quacks treated with 

 dog's excrement and urine. 



Treatment. As for other tape-worms. 



Echinococcus. (E. Hominis, Veterinorum, Polymor- 

 phus). The cystic or larval form of the echinococcus lives in a 



