the Origin of Intestinal Worms. 345 



surprised to find in almost every horse an aneurysmatical sac 

 filled with specimens of Strongylus annatus in the mesenteric 

 artery, near its origin from the aorta. The specimens here 

 are always young ones, whilst the old animals are generally 

 found in the larger intestines. {Fide Rudolphi, Entoz. Hist, 

 vol. ii. Pars i. pp. 205-207.) 



After I had observed the living young in the ova of the 

 Strongylus inflexus^ nothing appeared more explicable than 

 their method of passing from one porpoise to another. As 

 the worm frequents the bronchite, with its head immersed in 

 the substance of the lungs, and its tail extended into the larger 

 branches of the trachea, or into the trachea itself, the living 

 young at birth must naturally escape into the mouth, and as 

 porpoises commonly livein company, the young worms would, 

 by a short passage through the water, readily be introduced into 

 the mouth of another porpoise, and so reach the trachea. This 

 view appears the more probable, as, in company with the large 

 Stronggli infiexi, there commonly are found smaller ones ly- 

 ing loosely in the branches of the trachea, which Rudolphi 

 considers of the same species. This assertion, I maintain, 

 is erroneous. Tlic smaller ones have not only a different 

 shape, but their reproductive organs are as much developed 

 as are those of the large ones ; the penis is always protrud- 

 ed, and of a different shape, the uteri are full of ova and liv- 

 ing young. Thus, I cannot but regard these smaller worms 

 as of a different species, which I propose to designate Stron- 

 gglus vagans.* A certain condition of the lungs in the por- 

 poise appears favourable to the supposed migration of the 

 Strongyli inflexi. In almost all porpoises the lungs are full of 

 tubercles, each of which, on a closer inspection, is found to 

 contain a small worm rolled up like a ball. In this worm the 

 essential characters of the species cannot indeed be ascertained, 

 but as these characters are all taken from the reproductive or- 

 gans, this inability is the consequence of the organs not being 

 sufficiently developed. The young ones, of course, might be 



* Several reasons have induced mo to regard the Strongylits inJUxus as the 

 type of a peculiar genus, of which this smaller worm {Str. vagans) would bo 

 a second'species, and various others, found in other species of the Cetacea, 

 I hope soon to have an opportunity of describing. 



