226 



DISEASES OF FIELD & GARDEN CROPS. [CH. 







animals. We now see that the walls between the fur- 

 rows consist of elongated Oidium-like cells springing from 

 a gelatinous substratum, and each cell supports an Oidium 

 spore or conidium. These little spores or sporidia ger- 

 minate very readily in water or on any moist surface, and 

 by this means they not only continually increase the 

 Oidium growth, but they can, on being blown on to grass 

 flowers, cause the production of 

 other viscid early states of ergot. 

 It will be remembered that Oidium 

 Balsamii, Mont., reproduces itself in 

 the same manner on turnips ; 0. 

 monilioides, Lk., does so on grasses, 

 and 0. Tuckeri, B., on the vine. A 

 conidium or stylospore germinating 

 at A, and producing another stylo- 

 spore exactly like itself at B, is 

 shown at Fig. 106, enlarged 1000 

 diameters. As the true compacted 

 ergot below increases to its full 



FIG. 106. Spore of Spha- . ,, , J./TT- 



celia or Oidium of Ergot, slze > tne less compact Oidium growth 

 germinating at A, and above collapses and falls away. The 



producing a spore or true ergot j s t h en left devoid of its 



ZZSESL?^ viscid, watery apex, with its little 

 tortuous furrows and conidia or 



stylospores in the condition in which we first began our 

 observations upon it. 



The value of the Oidium growth to the ergot is obvious, 

 for if one needle-shaped spore from a Claviceps produces 

 the infant state of ergot on one rye-flower, we see that in 

 a few days this larval condition can produce thousands 

 of new Oidium spores, each spore being equally powerful 

 with a Claviceps spore in producing ergot. Ergots seldom 

 germinate and produce the Claviceps when more than a year 

 old ; two-year old examples have, however, been known 

 to sprout, but we have not heard of three-year old specimens 

 germinating. In concluding this subject we will mention 



