HEART-ROT 



103 



have occasionally been found. Each spore is attached to 

 the basidium by a very thin extension of the latter called 

 a sterigma (fig. 41, B, st.), and when ripe the spore which 

 develops at its extremity is cut off from the sterigma by 

 a transverse septum. The mature spores are hyaline, 

 measure 5-5-7 X 4-5-5 /u, and have a slight projection at one 

 side, where they are attached to the sterigmata. The 



FIG. 42. Diagram showing the necessity for the pores to be vertical. 

 In A, in which the orientation is correct, all the spores escape. In B, 

 which is tilted, only a small proportion of the spores escape from the 

 pores and the rest stick to the sides. For the sake of clearness the pores 

 are shown as much wider in proportion to their length than is the case 

 in F&mus annosus. For correct proportions the pores should be eight 

 times as long as in the diagram. The loss of spores through tilting would 

 then be much greater than that shown in the diagram. 



paraphyses are similar to the basidia in shape, but remain 

 sterile, and serve to keep the basidia at appropriate 

 distances. 



The spores, like those of most Hymenomycetes, are 

 slightly sticky, so that if they come in contact, during their 

 fall, with the sides of the pores, they adhere and fail to 

 escape. To prevent this it is necessary for the pores to be 

 exactly vertical, and the fungus, by some means not as yet 

 understood, has the power of making them grow in the 



