68 NATURAL HISTOEY, 



in India. They are so short and peculiar in appearance as to be hardly recognizable 

 as tapeworms. They give rise in some cases to severe irritation in the bowels. 

 What is the source of the most frequent tapeworm of the horse is not known, but 

 our knowledge of the development of other Tapeworms gives ns some clue. 



9. Thus the horse like other herbivora (but not nearly so frequently as the ox 

 and camel) has often in his liver and lungs, what are known as Hydatids or Hydatid 

 cysts. These look like white tumours, sometimes bigger than a cricket ball, in 

 other cases no bigger than a pea. When cut into liquid contents squirt out with 

 force often into the eyes of the enthusiastic student of Zoology. These contents 

 are watery for the most part, but have little white grains in them which, examined 

 under a low power, are found to be tapeworm heads ; the tumours, in fact, are the 

 cystic or bladder stage of development of the taenia which, more than mankind, 

 deserves Shakespeare's description, a one individual " in its time playing many 

 parts," its acts being seven ages — 



1. First the " Ovum" with its shell expelled into the world, 



2. And next the " sixhooked embryo" wandering free, 



3. Then boring through the tissues of the host becomes a " Cyst," 



4. Which nurse-like from its inner coat developes young, 



5. The " Scolices," on heads which bear a ring of hooks 



(5. Hydatids swallowed by flesh-feeders lose their coats, but many heads 

 7. Develope into fruitful Tapeworms and each segment bears ova in many 

 thousands to preserve the race. 



1 have never known a horse die from Hydatids, but cattle suffer much from fchem. 



10. The sharp tails (Oxyurides) must for the present complete our imperfect 

 enumeration of equine parasitic organisms. They are probably the most familiar, 

 because they reside in the terminal portion of the alimentary canal and are expelled 

 often in enormous numbers. Almost every horse brought in from the districts has 

 some of these worms. They are feeders on excrement, cause little mischief, and can 

 easily be recognised by their having a round firm body, and a soft tail-half to it. They 

 are something like a thick whip with lash as stout almost as and not long-er than the 

 handle. Although not very serious they cause irritation, and many a tail spoiled by 

 rubbing is due to the presence of these worms- One of the most common and dis- 

 tinctive indications of their presence is a brownish white deposit around theposterior 

 outlet of the alimentary canal, and sometimes a specimen will be found to have become 

 entangled in its passage through the opening. Syces bring specimens with great 

 triumph as proof of the necessity for a native worm medicine of considerable value, 

 Palas papra seed3. The best treatment, however, for the form of jiarasitic organism is 

 Injectio Terebinthinae. The larvre of Oxyurides hatch out in the earth, then enter 

 Borne animal in which they become changed into the hermaphrodite form. Those of 

 Ascarides and Filariae lie encapsuled in some animal, and with it pass into the 

 digestive system of some other animal-form in which they become adult ; those of 

 Strongyles live in the earth, and assume the adult condition in some animal ( Von 

 Linstow). Such are some of the remarkable variations in metamorphoses shown by 

 Nematodes. 



I trust my brief sketch has established my position that internal parasites are 

 worth studying by the naturalist, to whom nothing should be common or unclean ! 



