MISCELLANEOUS PAPERS. 261 



Busts, — The term rust is applied to those diseases which are caused 

 by species of the family uredineiB, or as they are often called, true 

 rusts. All rusts have, in most cases, three different stages. These 

 may or may not appear upon the same plant or host. The apple rust 

 is an exception ; it only has two stages. The three stages are known 

 as I, II and III, or also as iecidia, uredo, and telento or final stage. 

 My studies have been mostly confined upon clover and apple rust. 

 The first or ascidium stage of clover rust fUromyces trifolii J I have 

 only been able to find upon white clover fT. repensj, though I am in- 

 formed that in the East it is often found upon red clover. The spores 

 of this first stage are found in little cups, which are formed in clusters, 

 lience the name cluster-cups. On white clover they are found on the 

 petoile of the leaves, and are very strikingly yellow. They can be 

 readily seen with any good lens. 



These ;ecedial spores germinate quite readily, and give rise to a 

 (liff"erent plant-body, often upon a different plant or host, which bears 

 the second or ureda spores. These spores are capable of germinating 

 almost at once, providing of course climatic conditions are present, 

 and it is this stage that usually does the most harm, as in the rust of 

 wheat, oats and the various grasses. Toward fall another spore form 

 appears; this is known as the telento or final stage. These spores 

 have thicker walls, and do not germinate until the spring following, 

 when they germinate and give rise to the first or lecidial stage, and 

 thus commence the cycle of life anew. 



In the case of apple rust, there are only two stages, viz.: the I 

 and III — tecidial and telento. These grow on entirely different plants, 

 the first upon oedars and junipers, and the third upon trees related to 

 the apple family. For further information on this point, see my notes 

 on apple rust, in 34th annual report of Missouri H. S. 



Thus it will be Been that fungi bear seeds or spores similar to our 

 higher plants; they all require certain climatic conditions for their 

 development; it is therefore of the highest ioiportance that we should 

 become more familiar with these conditions, for if we do, our work of 

 destroying these can be pushed with more certainty of success. Some 

 of these spores retain their fertility for a long time, and can stand a 

 _great deal more exposure than is generally supposed. 



Prof. Scribner says that the spores of corn smut will pass through 

 pigs unharmed, and ihat their vitality may be preserved almost indefi- 

 nitely in manure piles. 



The spores of the wheat smut immersed in scalding water for 15 

 minutes will not be killed unless the water is heated above 30° F. ; if 



