44 MASSACHUSETTS HORTICULTURAL SOCIETY. 



The lecture was illustrated by large diagrams of the different 

 parts of several fungi, and also by specimens preserved in alcohol 

 and others mounted on cards. Some of the diagrams are repro- 

 duced here. 



Explanation of the Plates. 



Plate I. Wheat Rust {Puccinia Graminis Pers). Figure a 

 represents the teleutospores, or perfect state of the rust, as seen 

 on the stems and leaves of grains and other grasses, at the close of 

 the season and early in spring ; b a cross-section of the outer por- 

 tion of the stem, highly magnified, showing the ripe teleutospores 

 after the^^ have burst the epidermis ; c, teleutospores germinating 

 and producing the sporidia d d; e, barberry leaf, showing the un- 

 derside with its "cluster-cups" {cecidium form) ; /, one of these 

 cluster of cups somewhat enlarged ; g, a mature cup in cross-sec- 

 tion ; /i, one of the rows of spores as formed in the cup, highly mag- 

 nified ; ?', a magnified cross-section of grass leaf, with the uredo 

 state of the fungus after the spores have burst through the epider- 

 mis ; J, one of the uredo spores more highly magnified. 



Plate II. Grape Mildew {Peronospora viticola, B. and C.) a 

 represents a leaf of Vitis cordifoUa affected by the mildew ; &, a 

 cross-section of a grape leaf, much magnified, showing the filaments 

 of the fungus in the tissue, from which they finally pass out through 

 the stomata and form the asexual spore bearing the branched top c ; 

 d is a highly magnified -VTiew of the filaments in the leaf, with their 

 haustoria or " suckers," e e, penetrating through the neighboring 

 cell-walls ; /, one of the sporangia from c, highly magnified, and 

 dividing up into zoospores ; g, a zoospore ; h, a large sexual spore, 

 separated from the grape tissue in which it is formed. 



Plate III. Black Knot (Sphceria morbosa Schw). a repre- 

 sents a mature black knot ; 6, a cross-section of the same, and the 

 stem which bears it ; c, enlarged view of first form of asexual spores, 

 borne on filaments over the surface of the knot ; d, stylospores — a 

 second form of asexual spores formed in pits of the knot ; e, a peri- 

 thecium in cross-section, showing the sexual spores borne in sacs ; 

 /, two of these sacs with their spores, highly magnified, and a num- 

 ber of paraphyses, or sterile threads, around them. 



Figures d, f, g, and h of plate II, and b, c, d, e, and/ of plate III, 

 are drawn from figures by Dr. Farlow, in Vol. I, Part V, of the 

 " Bulletin of the Bussey Institution." 



