1 66 MUCOR 



in a saccharine solution. When the hyphse are submerged 

 in such a fluid they have been found to break up, forming 

 rounded cells (Fig. 37, K 1 , K 2 ), which not only resemble 

 yeast-cells in appearance but are able like them to set up 

 alcoholic fermentation. 



The aerial hyphse of Mucor exhibit in an interesting way 

 what is known as heliotropism, i.e., a tendency to turn to- 

 wards the light. This is very marked if a growth of the 

 fungus is placed in a room lighted from one side : the long 

 aerial hyphae all bend towards the window. This is due to 

 the fact that growth is more rapid on the side of each hypha 

 turned away from the light than on the more strongly 

 illuminated aspect. 



