4 MANUAL OF BOTANY 



plants in which certain of their cells perform the function of 

 nutritioii, while others are set apart for the purpose of repro- 

 duction. Thus, in the Moulds, such as Mucor {fig. 3), or 

 Eurotium (fig. 4), the cells which serve as organs of nutrition 

 are elongated simple or branched filaments, termed hyphcB, 

 which lie upon the surface and burrow in the mass of the sub- 

 stance furnishing the plants with food ; while others, destined 

 to reproduce the individual, are developed in globular cavities 

 (sporangia), as in Mucor (fig. 3) ; or are arranged in necklace- 

 like branches at the end of special filaments, as in Eurotium 

 (fig. 4). 



Fig. 3. 



Fiij. 3. A species of monld (Mucor) with branched mycelium composed of hypliie 

 aud bearing two sporangia X-, shown more liigiily magnified at 7. ^ ' 



Yet a little higher in the scale of vegetable life we find the 

 cells so combined as to form leaf-like expansions (fig. 5), or 

 solid axes (fig. 6), as well as special organs of reproduction 

 (fig. 5, t, t). But the cells are all more or less alike, so that 

 no true distinction can be drawn between the often very different- 

 looking parts we meet with in such plants as a seaweed or a 

 mushroom. Such a combination -of simOar cells, whatever the 

 precise form may be, which presents no differentiation of leaf 

 and stem, is called a thallas or t hallo me. The plants which 

 are commonly known as Algae and Fungi usually possess such 

 a plant body, and they have been grouped together to form a 



