102 



Dr. Drummond on the Equivocal 



alvine excretions, and therefore the circumstance of a speci- 

 men being found in water inhabited by fish of any kind may 

 amount only to this, that it had originally belonged to the fish. 

 Thus the celebrated Muller, when travelling on the borders 

 of Sweden, was told of a rivulet in which Taeniae were to be 

 found ; he visited it accordingly, and satisfied himself that the 

 account was true, by taking out of its water bundles of dead 

 Tape- worms coiled together. But what then? Did he find any- 

 thing more? Yes, he found quantities of the intestines offish 

 which had been thrown in by the fishermen, which fairly ac- 

 counted for the presence of the worms. (Rud. i. 373*.) No 

 one who has been in the practice of examining the intestines 

 of fishes in pursuit of their living contents, will be surprised at 

 this account, since the quantity of tape-worm sometimes 

 found in them is often almost incredible. Thus in a salmon 

 of eleven pounds weight, in July, 1838, I found a number of 

 Bothriocephalic the longest of which was four feet ten inches, 

 and their united lengths amounted to upwards of fifty-nine 

 feet. In the common Cod their number is often very great, 

 and in a middle-sized turbot I have found upwards of two 

 hundred specimens of the Bothriocephalus punctatus, each 

 measuring from ten to eighteen inches in length. 



It would be unnecessary to dwell longer on this subject, as 

 I believe all Helminthologists, and all who have considered it, 

 are fully agreed that the Entozoa have their natural abode in 

 the animal body alone, and that in any other situation they 

 infallibly perish. But the more difficult question is, how do 

 they get there ? 



This query cannot at present be satisfactorily solved, for 

 the truth is that we know nothing of their origin ; but I am 

 not inclined therefore to suppose them to be the entities of 

 equivocal generation, a doctrine still indulged in by natural- 

 ists and physiologists of high name and authority, and which 

 formerly was generally embraced with regard to all animals 

 occupying the lower links in the great chain of animated 

 being. 



But as the light of science burned bright, innumerable 

 errors were by slow degrees seen into, and have long since 

 ceased to blot the page of truth. They arose out of ignorance ; 

 and to a similar origin we are, I believe, to attribute the theory 

 of equivocal generation, whether it be applied to a fungus, 



* At a place about a quarter of a mile beyond Belfast Bridge, on Bally- 

 macarret Strand, where worn-out horses are slaughtered, I have more than 

 once seen dead Tsenise in a pool of water, but there could be no doubt that 

 their original habitat had been the intestines of the slaughtered animals, 

 dragged to the said pool by dogs, or kicked into it by idle boys. — J. L. D. 



