182 M.. 11. Krabbe on the Entozoa of Man and 



as I had the opportunity of verifying at the museum of the 

 University, where I examined a great number, chiefly collected 

 in Greenland. Among these was B. cordatus, the commonest 

 cestoid worm in the dogs of Greenland, but which also inhabits, 

 besides man, Phoca harbata and Trichechus Rosmarus, It is 

 not, however, in this Bothriocephalus that the phenomenon in 

 question is met with, but in the species which I have called B. 

 variabilis (from Phoca cristata and barbata) and B. fasciatus 

 (from P. hispida). 



It is particularly remarkable that whilst Tcenia cucumerina is 

 very common in the dogs of Iceland, I did not once meet with 

 T. elliptica in the cats — a fact which renders the distinctness of 

 these two species probable. 



It is incontestable that in Iceland the Echinococci are the cause 

 of one of the most dangerous maladies of man that exist in that 

 country. Nevertheless its frequency has been somewhat exag- 

 gerated. M. Schleisner^s opinion, that one-seventh of the inha- 

 bitants are attacked by it, is founded partly only upon a mere 

 estimate. From observations collected during six years by 

 M. Fin sen, a physician in the north of Iceland, we must infer 

 that the number of persons affected by Echinococci in a degree 

 sufficient to allow the malady to be recognized is between one- 

 fortieth and one-fiftieth of the population, which, indeed, is a 

 high number. 



Moreover it is always the Echinococcus, and not any other 

 vesicular worm, that attacks the Icelanders. With regard to 

 Cysticercus tenuicollis, mentioned with some reserve by Eschricht, 

 the case to which he called attention no doubt rests upon an 

 error: there is nothing to render probable the appearance of 

 this worm in the human subject in Iceland. 



According to Leuckart, the Echinococci of man and the do- 

 mestic animals belong to a single species; and the researches 

 that I was able to make in Iceland tend to confirm his assertion. 

 It is by means of experiment, as indicated by Leuckart, that we 

 must seek to test this opinion; and of six experiments made 

 by me, in concert with M. Finsen, there are two which at least 

 render it probable, and a third which can leave no doubt, as it 

 had exactly the same result as a similar experiment made the 

 same year at Berlin by M. Naunyn. Both of us have thus 

 obtained the transformation of Echinococci procured from the 

 human subject into Taenia echinococcus in the dog. In Iceland 

 this little Taenia occurs in the dogs with extraordinary frequency; 

 and both the large and small cattle harbour great numbers of 

 vesicular worms, which furnish those animals with their cystic 

 Tsenias, namely Echinococcus ^ Cijsticercus tenuicollis, and Coenu- 

 rus cerebralis. On comparing 100 Icelandic dogs which I ex- 



