NEMATODA. 769 



produces very serious or even fatal consequences; and 

 thus it happens, that in proportion to the quantity of 

 imported parasites the symptoms resulting will be either 

 severe, dangerous, or even fatal. 



It has been stated by some writers that even pigs occasionally 

 display symptoms of trichiniasis, the signs of the disease in the 

 animal being loss of appetite, quiescence, aversion to all kinds 

 of movement, and even partial paralysis of the limbs. In the 

 human subject it is well known that the symptoms are much 

 more severe, many of the patients enduring the most intolerable 

 agony, until at length death mercifully comes to put an end to 

 their sufferings. 



Here it will not be out of place to mention that cats are liable 

 to be affected with another disease very closely resembling 

 trichiniasis, which may appropriately be called olulaniasis. The 

 disorder is occasioned by a minute trichina-like nematode termed 

 by Leuckart Olulanus tricuspis. It gains access to the lungs in 

 the larval state, producing death by suffocation. 



Our knowledge of the history of the development of the larger 

 round-worms is very incomplete ; nevertheless the causes of the 

 prevalence of these worms in particular localities and during 

 certain seasons are not far to seek. It is clear that their final 

 stage of growth is accomplished with great rapidity, otherwise 

 we should not meet with lumbricoids in pigs and puppies scarcely 

 three weeks old. Large round-worms have also been found in 

 very young colts. The ordinary lumbricoids of the horse, of the 

 pig, and of man, so very closely resemble each other, that by 

 some they are regarded as mere varieties of one species {Ascaris 

 mcgaloccpliala, A. suilla, and A. lumbricoides). Whether they 

 are so or not is of little practical moment, for it seems quite 

 certain that a perfect knowledge of the earlier stages of develop- 

 ment of any one of them would furnish a clue as to what obtains 

 in the others. It is probable also that the lumbricoids of the 

 dog and cat undergo similar clianges. 



The eggs of the common round-worm have been kept alive 

 by Davaiue for more than five years ; and various observers 

 have watched their development in fresh water up to the stage 

 of imperfectly developed embryos, and have kept them alive in 

 this condition for three months. 



