Intestinal Parasites of the Dog. 317 



similarly matured the larvae by feeding them to dog and man. It 

 carl therefore be taken for granted that the normal source of 

 bothriocephalus for man and dog is through devouring the larvae 

 in fresh fish. In addition to the pike and turbot, the tench, 

 grayling, perch and other fishes harbor the larvae. Other exper- 

 iments, however, seem to show that the larval stage in the fish is 

 not essential, but that B. I,atus may be developed from the ovum 

 to maturity in the intestine of the dog. 



Bothriocephalus Cordatus. Heart-shaped B. This form 

 is smaller than B. Latus, being when mature 2j^ to 4 feet long, 

 and having 400 to 600 segments. Its striking features are that 

 the head is heart-shaped (obcordate), compressed from side to 

 side and broadest from above downward, and with two bothridia, 

 one on the upper and the other on the lower margin. It has no 

 neck, but broadens rapidly, shows segmentation from the head 

 backward, and reaches its greatest breadth at 6 cm. behind the 

 head. The uterine rosette is longer and more branching, but of 

 smaller calibre than in B. Latus, and the body contains more 

 calcareous particles. 



Orlik found B. Cordatus very prevalent in the dogs of God- 

 haven, N. Greenland, six dogs furnishing as many as 20 speci- 

 mens. Pfaff found 24 in three dogs, and one in a seal. Zimmer 

 found the worm in a walrus. It was much less frequent in man, 

 and has not been found out of Greenland. This speaks for its 

 transmission in larval form through the fish of the Greenland 

 Seas to the marine and terrestrial mammalia of the locality. 



Bothriocephalus Fuscus. Dark B. This worm is 3 to 27 

 inches long, with flat, lanceolate head, and segments beginning 

 near the head and encreasing until longer than broad. The ovi- 

 ducts show as a dark-blue spot in the centre of the segment and 

 suggest the name. Calcareous particles are absent. Krabbe 

 found this in two dogs in Iceland, one having 22 specimens of 

 different sizes. 



B. Reticulatus and B. Dubius are two closely allied speci- 

 mens found in dogs in Iceland. 



The treatment of bothriocephalus is essentially the same as for 

 taenia. Prevention is to be sought in the thorough cooking of all 

 fish fed to dogs or men, and the exclusion of dogs from all 

 curing establishments or other places where they might get the 

 uncooked products. 



