INFLUENCE OF SEX, AGE, AND OCCUPATION. 641 



the other hand, the number of observations is so small, that it is quite 

 possible there has been some error. 



It is almost unnecessary to say that the data which we have 

 obtained by clinical observations must not be held as directly appli- 

 cable to the general population. The proportion in which the Echino- 

 coccus occurs in the latter cannot at present be even approximately 

 estimated ; but at any rate it is much less frequent than Cysticercus 

 cellulosce, probably even in those districts of Germany in which it is 

 relatively most abundant. 



The explanation of the variable frequency of the Echinococcus is 

 always to be found in the different occupations and modes of life of 

 the inhabitants. The extent to which cattle and sheep are reared, the 

 number and treatment of the dogs, and the varying degree of cleanli- 

 ness, are the principal factors by which it is determined ; and this is 

 true not only of the different countries which are geographically and 

 climatically distinct, but also of much more restricted limits. This 

 explains why the Echinococcus occurs more rarely in towns, and 

 especially in large towns, than in the country, where the slaughtered 

 meat is less strictly inspected, and the dog not only has more frequent 

 opportunities of becoming infected with Echinococcus-he&ds, x but is 

 allowed more unrestricted intercourse with man. Similarly, it appears 

 that herdsmen and shepherds, with the members of their family, 

 furnish an unusually large contingent to the number of Echinococcus 

 patients, and at any rate a much larger one than seamen, among 

 whom, as has already (1846) been shown by Budd, this bladder- 

 worm is extremely rare. The fact mentioned by Busk, that the 

 lower classes are more frequently subject to infection than the 

 higher, must be ascribed essentially to the want of order and cleanli- 

 ness among the former, and thus to circumstances which also affect 

 the frequency of Cysticercus cellulosce. On the other hand, we know 

 of persons of a higher rank who have been infected with Echinococcus, 

 usually, indeed, in consequence of two close intercourse with pet dogs. 

 To the same circumstance is perhaps to be referred the somewhat 

 mysterious preponderance of female patients, which, according to the 

 statistics of Neisser, amounts to nearly a third (210 : 148), and is all 

 the more striking, since it will be remembered that in Cysticercus 

 cellulosce we had to note exactly the opposite proportions. It is, how- 

 ever, true according to Finsen that this preponderance of the female 

 Echinococcus patients is also found in Iceland (255 : 181), where no 

 pet dogs are kept. 2 



1 With this agrees the statement of Krabbe, that the dogs in which he found Tcenia 

 echinococcus came principally from the suburbs of Copenhagen, Archiv f. Naturgesch. , 

 loc. cit., p. 120. 



2 We may take this opportunity of remarking that the cases hitherto observed of 



2 S 



