197 



The first to appear called spermatia arise in small cup-like recep* 

 tacles on the upper surface of the leaf. They are very minute, 

 and their function is at present unknown. On the under-surface 

 of the leaf, larger, golden-yellow, cup -like receptacles arise, which 

 are clearly visible to the naked eye and are often, known by 

 the popular term of "cluster-cups". These cups have fringed, 

 white margins and are rilled with golden-yellow spores. They 

 arise first beneath the epidermis as hollow balls, the membranous 

 walls of which are formed by the fungal hyphse and constitute 

 what is known as the peridium. The base of these balls is 

 formed by a number of short hyphae with their ends directed 

 towards the apex of the ball. From the ends of these hyphae 

 spores are ab jointed in succession from the apex downwards, 

 long chains of spores being thus produced. As the formation 

 of spores proceeds, the ball swells and ultimately the epidermis 

 of the leaf and the peridium covering are ruptured and the ball 

 becomes a cup-shaped receptacle projecting from the leaf sur- 

 face. As the spores escape from these receptacles and are dis- 

 tributed by the wind, fresh ones are developed from the hyphae 

 at the base to replace them. See Plate XIX (4), (5) and (6). This 

 form of the fungus developed upon the Berberis was at first 

 thought to belong to a distinct genus from that which included 

 the form occurring on the wheat ; it consequently received the 

 name of Aecidium Berberidis, and it was long before the connec- 

 tion between the two was established. The cluster cups are 

 called aecidia and the spores developed in them aecidiospores. 

 These spores are very like the uredospores except that they are 

 more golden-yellow in colour and are often somewhat polygonal 

 in form, owing to the pressure which they have undergone. 

 These spores, alighting on a damp wheat plant, send out germ 

 tubes which, finding their way through the stomata, give rise to 

 the mycelium in the plant tissue from which uredo- and teleuto- 

 spores are ultimately produced as before. Aecidium Berberidis 

 is found on Berberis Lycium near Simla and also probably occurs 

 on other Indian species of Berberis. 



We thus see that the complete life-history of this fungus 

 comprises two distinct stages which may be called the Pucci- 

 nial and Aecidial respectively, and these stages may be sub- 

 divided into four as follows : 



C (1) The parasitic mycelium in the wheat 

 Puccinial I plant developed from aecidiospores and 



, "! giving rise to uredospores. 



i (2) The formation of teleutospores from 



Lthe same mycelium. 



