MILDEW AND BRAND. 59 



and the microscope, we proceed to examine them 

 in the same manner as we have already examined 

 the mildew, and as a result of such proceeding 

 arrive at the following conclusions : — The pustules 

 are small and round, never elongated as in the corn 

 mildew, and generally confined to the under surface 

 of the leaves (plate IV. fig. 69). The spores are sub- 

 globose, slightly constricted, and the two cells nearly 

 two hemispheres, with their flat surfaces turned to- 

 wards each other (fig. 70). The form delineated in 

 figure 75 is that of the sorus of many of the epi- 

 phytal brands, the centre being occupied by the 

 closely-packed spores, surrounded to a greater or 

 less extent by the remains of the ruptured 

 epidermis. 



Although the species of Puccinia (P. glechomatis) 

 found on the leaves of the ground-ivy is said to be 

 very common, we sought it in vain amongst every 

 cluster of that plant met with during last summer 

 and autumn, until, nearly despairing of finding it 

 at all, we at last encountered a plot of ground-ivy 

 covering the ground to the width of two or three 

 yards, and in length eight or ten, nearly every plant 

 being attacked by the brand. This was in the 

 corner of a pasture, and the only time we found 

 infected plants. The fungus, however, may be as 

 common as the plant in other localities. The pus- 

 tules on the leaves are larger than those of the 

 mints, and also confined to the inferior surface 

 (fig. 73). The spores are elliptic and but slightly 



