208 AGEICULTURAL EXPERIMENT STATION. [Jan. 



A few closely related plants belonging to the group of 

 rusts constitute important exceptions to the typical life 

 history, outlined above. These are hetermcismal fungi, 

 whose second form is unknown, and probably does not 

 exist. Their cluster-cup forms cause the familiar " rusting" 

 of the leaves, and sometimes of the fruits, of apple trees, 

 hawthorns and related woody plants, in summer ; and their 

 third forms are the " cedar apples," whose gelatinous fruiting 

 masses are equally common on our red cedars or " savins" 

 and junipers, in spring. It will be seen from the above that 

 the " pedar apples," which correspond to the black-rust stage 

 of other rusts, appear earlier in the season than the cluster- 

 ciip stage ; naturally, then, their spores are not resting 

 spores, the fungi being carried through the winter by their 

 mycelia, which live in the branches of the hosts. 



Among important isolated forms, whose other stages are 

 unknown, may be named the orange-colored rust which 

 covers the lower surfaces of the leaves of blackberries and 

 raspberries in spring and summer. 



8. Jelly fungi (^Tremellini) are very interesting botani- 

 cally, since they show distinct relationships with both the 

 rusts and the toadstools ; but they are saprophytes, and 

 require no further notice here, beyond the statement that 

 they form gelatinous masses of various colors, from white to 

 black, on dead wood, and are most abundant in late fall and 

 early spring. 



9. Toadstools {Hymenomycetes) are perhaps the most 

 abundant of fungi, besides comprising more species than any 

 other group. They are nearly all saprophytes, and many 

 grow in places where the presence of organized food 

 material would hardly be suspected. Their spores are borne 

 free at the ends of spore-producing threads, which are 

 usually packed closely together, and form a fruiting surface. 

 In the siui[)lest members of the group this surface is the 

 only one exposed to the air ; but in the more elaborate 

 forms, popularly known as toadstools, there are upper and 

 under surfaces distinguishable on the fruiting structure, and 

 of these the latter is the spore-producing surface. 



A few forms are of present interest. One of the simplest 

 members of this group causes the leaves and fruits of the 



