602 GLOSSARY. OSMOSIS PARASITE. 



He mentions the case of a neighbour of his who, in sowing down 

 a field, used a mixture of grass-seed with some parsley-seed, upon 

 which the mutton obtained from the sheep fed in this field gained 

 the flavour of parsley. On this subject, he calls attention to the 

 fact, that boiled and pulped turnips do not give to the milk and 

 butter of cows fed thereon the same amount of turnip flavour as 

 when consumed raw. 



To these cases may be added one in the experience of one of us, 

 where the milk of cows acquired the flavour of almonds, on account 

 of having eaten the prunings of a laurel bay that lay by the road- 

 side. The milk was rather prized for this flavour, but a boy who 

 used much of the milk daily was nearly poisoned. 



OSMOSIS. See Endosmosis. 



OVALBUMEN. See Albumen. 



OVARIES. See Genital Organs. 



OXYGEN. The gaseous constituent of the atmosphere essential to 

 animal life. It makes about one-fifth part of common air, and is 

 one of the constituents of organic structure. See p. 292. 



PANCREAS. The sweetbread. 



PARASITE, PARASITIC. Words applying to both plants and animals, 

 that instead of leading an independent existence, live on or in the 

 bodies of plants or of other animals, and draw their substance there- 

 from. The subject of parasitic existence grows in importance every 

 day. The misletoe ( Viscum album) is an example of a parasitic 

 plant ; it grows chiefly on apple-trees. Cuscuta dodder is a genus 

 of parasitic plants, of which the Cuscuta epilinum, flax dodder, is 

 sometimes very injurious to flax crops. Under the name of epi- 

 phytes, parasitic vegetable structures of a character most destruc- 

 tive both to living plants and living animals have been observed 

 and described. These epiphytes are of microscopic character, and 

 belong to the lowest order of vegetable existence namely, to the 

 fungi. By their presence they produce blights in plants, and dis- 

 eases of the skin and of the mucous membrane in animals. Fungi 

 of this description commit inconceivable ravages under circum- 

 stances favourable to their propagation among silk-worms. 

 Tinea or scald-head owes its origin to a fungous growth of this 

 nature. Some forms of tinea can be propagated from horses and 

 oxen to men, by the transmission of the parasite to which it owes 

 its origin. Favus, which is a kindred cutaneous disease, is believed 

 to be propagated to children from cats, dogs, and mice, by means 

 of a fungus which obtains its first development on the mouse. 

 Animals seem to contract such diseases from the human body ; and 

 the fungus on which the mange in the cat is dependent, seems to be 

 the same on which tinea depends in man. 



