110 



TRUFFLES. 



35. The division of the Lycopodia cece comprises mushrooms, 

 the sporules of which are not enclosed in especial capsules. We 

 place among them truffles (Jig. 129), singular plants of irregu- 

 larly rounded form, which grow under ground without being 

 attached to any other body and without ever appearing above the 

 surface. The edible truffle, so much esteem- 

 ed by gourmands, is of a brown colour, 



strong odour, and peculiar taste ; its size 

 varies from that of an egg to that of a fist, 

 and it grows five or six inches under ground. 

 It is chiefly met with in forests of ash, chest- _,. " 



i i -i i f i .riff. Iz 



nut, or oak, and in soils composed of sand 

 and clay. To gather these subterranean mushrooms we take 

 advantage of the instinct of hogs, which root them up with their 

 snout. They have not been multiplied by cultivation as yet. 



36. The mucedinece or moulds are also plants of the family 

 of Fungi, and we also place in this natural division certain 

 parasitic plants that grow on other living plants, often producing 

 in them very remarkable injurious alterations. Of this number 

 is a species of fungus named aredo, which is sometimes developed 

 on wheat, and occasions what farmers call blight. 



37. The FAMILY OF ALG^E Sea- 

 weeds is composed of marine arid 

 other aquatic plants, the structure of 

 which is very simple. The fuel which 

 cover the rocks on our coast belong 

 to this group. The genus Fucus (Jig. 

 130) yields iodine, a useful medicine. 

 The Chondrus crispus or Carageen 

 moss of Ireland, which also grows on 

 our own coast, is converted into size ; 

 it also yields a fine jelly for invalids, 

 and is often used in the composition of 

 blancmange. 



38. The SEMI-VASCULAR PLANTS 

 are at first composed of cellular tis- 

 sue alone like cellular plants, but often acquire, at a certain 

 period of their development, vessels and stomata like phanero'- 

 gamous plants. They are provided with roots like the latter, 



35. What species of mushroom belong to the division of Lycopodia cea; ? 

 What are the general characters of the edible truffle ? Where are they 

 found ? Are they cultivated ? 



36. What are mucedi'neffi ? What is aredo ? 



37. What are Algae ? What do we obtain from the genus Fucus ? 



38. What are the general characters of the semi-vascular plants ? 



Fig. 130. FUCUS. 



