MICROSCOPIC PLANTS. 17 



are the cause of mildewed corn, and recent scientific 

 investigations have shown that there is truth in the 



FIG. 18. FIG. 19. 



belief, which is not always the case with popular 

 adages. Dr. M. C. Cooke, in his " Fungi," gives the 

 following : 



" There is a village in Norfolk, not far from Great 

 Yarmouth, called ' Mildew Rollesby,' because of its 

 unenviable notoriety in days past for mildewed corn, 

 produced, it was said, by the Berberry bushes, which 

 were cut down, and then mildew disappeared from 

 the cornfields, so that Rollesby no longer merited its 

 sobriquet. It has already been shown that the corn- 

 mildew (Puccinia graminis) is dimorphous, having a 

 one-celled fruit (Trichobasis), as well as a two-celled 

 fruit (Puccinia). The fungus which attacks the Ber- 

 berry is a species of Cluster-cup (d&cidium berberidis) 

 in which little cup-like peridia, containing bright 

 orange pseudospores, are produced in tufts or clusters 

 on the green leaves, together with their spermogonia. 

 De Bary's observations on this association of forms 

 were published in 1865. In view of the popular 

 belief, he determined to sow the spores of Pticcinia 

 graminis on the leaves of the Berberry. For this 

 purpose he selected the septate resting spores from 

 Poa pratensis and Triticum repens. Having caused 

 the spores to germinate in a moist atmosphere, he 



