162 DISEASES OF FIELD & GARDEN CROPS. [CH. 



being rent. These cups may be compared with, the 

 dScidium cups of the allied JE. asperifolii, Pers., illustrated 

 to the same scale in Fig. 71. At EEE three of the 

 little black sperm ogones are seen in section. In the 

 middle of the leaf, at FF, amongst the green cells, may be 

 seen a longitudinally cut mass of vascular tissue or spiral 

 vessels belonging to one of the veins. The abnormal 

 thickness of the leaf caused by the presence of the fungus 

 is shown at GH. An embedded unripe spermogonium is 

 shown at J, and an organ of transpiration at K. 



From a large number of observations made with the 

 view to trace the origin of the ^cidium cups and the 

 spermogonia in the barberry, we believe it takes place 

 in the following manner : If sections are repeatedly 

 taken through affected barberry leaves it will be seen that 

 numerous minute granules and extremely small disjointed 

 fragments of mycelium may be seen in the intercellular 

 spaces. The fragments and granules vanish by degrees into 

 the finest dust at one end of the series, and appear as short 

 threads at the other and growing end. As the disease 

 advances the granules extend in growth, and appear as 

 fine yellowish-orange tubular mycelial threads furnished 

 with septa. This mycelium has a natural tendency to 

 grow towards both surfaces of the leaf, the growth becom- 

 ing more profuse as the surfaces are neared. When the 

 mycelium has reached the epidermal cells, under and 

 upper, it forms minute compact knots ; the upper knots at 

 length become the spermogonia, and the lower the dEcidium 

 cups. 



At Fig. 84 is represented a section through an JEcidium 

 cup, enlarged 150 diameters. The lower epidermis of the 

 leaf is shown at AB, ruptured by the fungus from within 

 at CD. The fine septate, almost granular, mycelium, 

 from which the fungus springs, is shown at the top of the 

 illustration at D, and creeping amongst the intercellular 

 spaces at E. The outer coat, or peridium, of the cup, 

 consisting of a single stratum of transparent polyhedral 



