166 DISEASES OF FIELD & GARDEN CROPS. [CH. 



from which the cups and spermogonia arose, breaks up 

 into the finest conceivable dust, or dissolves away, and so 

 is lost to sight. 



A single dEcidium spore is enlarged to 1000 diameters 

 at Fig. 86. To the spore are attached four of the so-called 



- 1000- 



FIG. 86. 



Germinating spore of sEcidium Berberidis, Pers. 

 Enlarged 1000 diameters. 



spermatia from the spermogones, just as one commonly 

 sees pollen-grains agglutinated on to a stigma. 



The spores germinate rather sluggishly on damp sur- 

 faces, but when seen in a state of germination a mycelial 

 thread is protruded in a convolute fashion from one of 

 about six privileged or weak points on the surface of the 

 spore. Into the mycelial thread the vital material from 

 the spore is poured. 



The tardy germination of the spores seems to indicate 

 that they are of the nature of resting-spores, and therefore 

 able, under suitable conditions, of resting for a prolonged 

 time. It is generally believed that the spores arise from 

 male and female elements, and these facts indicate to some 

 observers that the cycle of the ^Ecidium is complete in 

 the production of these spores, or that no other spores are 

 likely to exist unless simple conidia or bud spores, as 

 opposed to resting or sexually-produced spores. 



Of late considerable attention has been directed to the 

 fact of the occurrence of ^cidium Berberidis, Pers., on the 

 more ornamental species of barberry of our gardens and 

 shrubberies, and especially its growth upon Mahonia 

 Aquifolium, Lindl. The rare occurrence of the parasite 



