26 MICROSCOPIC FUXGI. 



In many of the species of ^cidium the cups are 

 disposed in a more or less regular circle,, the centre 

 of which is occupied by a group of spermogones ; at 

 the same time^ the corresponding spot on the 

 opposite surface of the leaf will frequently be found 

 also occupied by other spermogones — in some 

 instances in greater number than on the same surface 

 of the leaf on which the cups are seated. This is 

 the case in the ^cidium which is found upon the 

 leaves of the coltsfoot^ and that of the honeysuckle. 



Yery bright orange-coloured spots may be ob- 

 served in autumn (we have encountered them often 

 in August and September) upon the leaves of pear 

 trees^ and which are covered with little tubercles, 

 at first of the same colom^ but ultimately becoming 

 brown. These pustules are so many spermogones 

 belonging to Ecestelia cancellata, a kind of cluster- 

 cup found in the same localities. These spots have 

 long since been noticed, and regarded as connected 

 with the Rcestelia, but in what manner has until 

 recently been unknown. The Eev. M. J. Berkeley 

 noticed them in the English Flora in 1836, or at least 

 the granulations on the upper surfaces of the leaves 

 beaiing R. cancellata, R. cornuta, and R. lacerata, 

 and called them abortive pseudoperidia. Before this 

 (in 1804) they had been observed by Eebentisch. 

 An examination of one of these spots under a low 

 power of the microscope, and afterwards a section 

 of one or more of the pustules, cut with a sharp 

 razor, and viewed with a higher power, will give an 



