STATISTICS OF OCCURRENCE OF HELMINTHS. 151 



well worth striving for, since it means nothing else than the health 

 and weal of many thousands. This is no exaggeration ; we have 

 already noted the devastation which the Dochmius intestinalis makes 

 among the Fellahs of Egypt, and we know of similar occurrences in 

 other places. According to the report of Schleissner and Thorstensen, 

 a seventh part of the population of Iceland suffer from Echinococcus * 

 and in tropical countries of the old and new world diseases caused by 

 worms are among the most frequent and widely distributed, e.g., tape- 

 worm, dracontiasis, hsematuria, chlorosis, and dysentery. 



ETIOLOGY. 



Our positive results as to the transference of human worm 

 parasites are still unfortunately very far from complete; we must 

 therefore content ourselves to a large extent with suggestions and 

 deductive conclusions. The following remarks, therefore, make no 

 pretension to exhaust the subject, but they nevertheless contain almost 

 all that we are as yet warranted in maintaining. 



We may first summarise in a sentence the chief result of our 

 previous study of parasitic worms, viz., that the great majority of 

 these creatures inhabit different animals in their different stages. If 

 we apply this sentence to those infesting man, we see at once the 

 probability of the conclusion, that we derive a large proportion, and in 

 all likelihood by far the largest proportion, of our parasites from other 

 animals* Specially, then, must those animals be considered with 

 which we come into contact in any way, and, above all, those domestic 

 animals which are used as food. 



1 Echinococcus is widely distributed in Asia and Australia, and is, according to 

 Schleissner, the most frequent of all diseases in Iceland. In 2600 cases of illness men- 

 tioned in the medical reports, 328 were afflicted with Echinococcus in the liver ; and out 

 of 327 private patients, 57. According to Krabbe, these results are not accurate, and by 

 no means applicable to every district of Iceland. (Archiv f. Naturgesch., Jahrg. xxxi., 

 Bd. i., p. 114, 1865.) According to a calculation of Finsen's for the northern part of the 

 island, Krabbe would conclude that only -^ or ^ of the population can be proved to be 

 suffering from Echinococcus. But even this is a very large number. 



2 A complete statistical account of the human Entozoa even of civilised Europe is still 

 a desideratum. An effort has recently been made in this direction, on the basis of clinical 

 dissections, K. Muller, " Statistik menschl. Entozoen : " Erlangen, 1872, based on the 

 results of the autopsies in Erlangen and Dresden ; and H. Gribbohm, " Zur Statistik der 

 menschlichen Entozoen :" Kiel, 1877. From these results we learn that among us Tricho- 

 ccphalus, Oxyuris, and Ascaris are by far the most common Helminths. In Erlangen 

 there were found, among 1755 bodies, 227 with Ascaris (12'9 p. c.), 213 with Oxyuris 

 (12-13 p. c.), 195 with Trichocephalu* (11 '11 p, c.). Among these 138 post mortem exami- 

 nations of insane patients from the asylum are not included, in whom round- worms were 

 always found, sometimes only one species, sometimes several. In Dresden (out of 1939 

 post mortem sections) the numbers were much smaller, Ascaris in 9'1 p. c., Oxyuris in 2'1 



