1 1 1 6 General Notes. [Dec. 



troublesome in American green-houses, suggests a similar cause. 

 Among those on woody stems are the black knot on species of 

 Prunus and the Gymnosporangia on cedars. 



The flower is attacked in the case of the " double blossom" of 

 blackberries, the smuts of many grasses (such as Ustilago raben- 

 horstiana on Paniciun sanguinale), and other cases that will sug- 

 gest themselves. Often the entire inflorescence is arrested in its 

 development. Smut of Indian corn attacks both staminate and 

 pistillate flowers, and the green parts as well. Ustilago anther- 

 annn upon Caryophyllaceae produces its spores in the anthers. 

 Tilletia caries, the bunt of wheat, destroys the inner structure of 

 the seed, without much changing the external appearance. The 

 majority of Ustilagineae attack the inflorescence, flowers, and 

 fruit. 



The young ovary is affected in various ways. Ergot distorts 

 it and produces an abnormal, horn-like mass of tissue ; smuts 

 convert it into powdery spores. Exoascus changes that of 

 Prunus into a pouch. Fusicladium kills the newly-formed pear. 



(5) The last case is also an example of the premature falling 

 of diseased parts, apparently by the formation of the separative 

 layer before its time. Such a falling of leaves is well illustrated 

 by Stptoria ribis upon the currant. On the other hand, diseased 

 parts may remain green after the other parts have matured in the 

 usual way. Ovaries of Eragrostis poceoides filled with Ustilago 

 spcniwpliorus are most readily detected by this sign. Probably 

 this may be classed as retarded development. 



(6) Many fungi cause decay of ripe fruit, both while attached 

 to its plant and after removal, while still alive. From a practical 

 stand-point, the injury to fruit maybe of two kinds; it may affect 

 simply the appearance, and hence the market-value, or impair 

 the quality, when it does not entirely destroy. The scab of 

 apples is injurious in either of these degrees. 



Some fungi begin their growth as parasites under ordinary 

 conditions, to continue it under conditions, more like those which 

 accompany saprophytic growth ; in this connection may be men- 

 tioned the potato-rot, beginning its growth upon the green plant 

 and sometimes completing it in the cellar, but upon the still 

 living tuber. 



(7) Some valuable plants are liable to infection from others of 

 less value; a knowledge of this fact in individual cases may be 

 of great practical utility, as a remedy may be more easily and 

 effectively applied. It is easier to destroy wild grapes and Am- 

 pelopsis than to destroy Peronospora upon cultivated grapes 

 which have suffered infection from the wild ones. This remedy 

 especially commends itself when one stage of the fungus grows 

 upon one kind of plant and another stage upon another kind, 

 as do cedar-apples and orchard-rusts. 



Perhaps no line of investigation in economic mycology prom- 



