204 UTILIZATION OF MINUTE LIFE. 



up immediately into an animal similar to its parent. 

 Often the young helminthe transforms itself into a 

 species of larva capable of giving birth, without 

 fecundation, to other larvce, which are alone capable 

 of becoming animals similar to the parent worm. 

 But the most curious portion of their history is that 

 these larvce are generally found in the tissue of ani- 

 mals very different from the one in which the perfect 

 worm exists, so that before one of them can complete 

 its development, and become a perfect worm, it must 

 be transported into another animal's body ! Thus it 

 is that Cysticercus cellulosa, Gm., which resembles a 

 white cell or vescicle, and constitutes a peculiar 

 disease with pigs, in whose muscular tissue it de- 

 velopes itself and multiplies with fearful rapidity, 

 transforms itself into Tcenia, or tapeworm, in the 

 intestines of the human body; in fact, Cysticercus 

 is the larvae of Tcenia* 



* But these details are foreign to my subject. I cannot, how- 

 ever, let pass this opportunity without noting down some recently 

 discovered facts relating to this interesting class of animals. Among 

 Helminthes, or Entozoa, as they are sometimes called, is a genus, 

 ttlaria, of which a species is often found in the heart of over-fed 

 sheep, etc. It was formerly thought that these Filaria underwent 

 no metamorphosis ; but M. Joly has lately discovered a number of 

 female nemato'id worms in the heart of a seal (Phoca vitulina) ; they 

 belonged evidently to the genus Filaria : the individuals measured 

 fifteen to twenty millimetres in length ; the species appeared to be 

 new, and was named Filaria Cordis phocce. It is supposed that this 

 worm is conveyed into the body of the seal by the fish which the 

 latter feeds upon, and in whose bodies it exists in the larva state, 



