344 Dr Eschricht*s Inquiries concerning 



necessarily throws light upon the mode of the propagation 

 of Helminthiasis, so the mode of the propagation of the dis- 

 ease serves, in its turn, as an argument for the common gene- 

 ration of the animals which produce it. This remark may be 

 applied to the Ccenurus cerehralis ; for the disease produced 

 by this worm, — the common sturdy, or gid, or giddiness of 

 sheep, — often rages amongst these animals as a virulent con- 

 tagion. The disastrous effects of the Distoma hepaticum^ — - 

 the fluke-worm, so well known in Rot, — are, in many countries, 

 an object of dread to the farmers : this worm, too, occurs in 

 man and calves, as well as in sheep. Among fishes, too, some 

 intestinal worms, e, g. the Bothriocephaliis soUclus in stickle- 

 backs, appears to rage in certain years like other contagious 

 diseases. 



The fact that intestinal worms have been found in new-born 

 animals, and even previous to birth, has been noticed as an un- 

 answerable proof of their spontaneous origin. How otherwise, 

 it is demanded, could these worms get into the] young ? This 

 inquiry should be met with another, Did it not exist in the mo- 

 ther ? In some instances we know that it did ; in the same 

 way that smallpox spreads from mother to child, although the 

 exact mode of communication cannot well be traced. 



If, then, intestinal worm.s get into the body as offspring of 

 other intestinal worms, the inquiry presents itself, what are the 

 various methods in which this actually happens 1 It has been 

 a great disadvantage to science, that the disbelievers in equi- 

 vocal generation have been satisfied with the supposition that 

 intestinal worms were always introduced into the body with 

 the food ; and also that the advocates of the doctrine, in their 

 laborious inquiries, have disregarded those appearances which 

 might have indicated the mode in which the Entozoa were ac- 

 tually introduced. The manner in which animals provide for 

 the safety of their offspring is known to be so exceedingly va- 

 rious, and peculiar even to each species, that it can scarcely 

 ever be conjectured beforehand. Hence there is but one way 

 of solving the problem, viz. inquiring into nature. As to the 

 Entozoa, the information hitherto obtained may be compre- 

 hended in the following- facts. 



o 



Sect. 2. The Entozoa verg commonig change their abode at 

 different periods of their /^<?.^— Every anatomist must have been 



