130 DISEASES OF FIELD & GARDEN CROPS. [CH. 



The term conceptacle explains itself; it simply means 

 a receptacle formed of one valve. Sometimes these bodies 

 are termed perithecia, or boxes enclosing the bladders, 

 termed asci or thecce. These bladders always in turn 

 enclose spores or sporidia. The conceptacles arise, it has 

 been said, at a point where two specialised threads of 

 spawn cross each other, and where the enlarged ends of 

 two spawn or mycelium tubes come in contact in a 

 manner similar, it has been said, with the contact of the 

 anther with its pollen with the stigma in flowering plants. 



X-200- 



FIG. 58. 



Horizontal section through a Conceptacle of Erysiphe graminis, B.C. 

 Enlarged 200 diameters. 



The conceptacle or perithecium, after it is once formed 

 on the mycelium, quickly grows in size, and speedily 

 acquires a brown or blackish tint. The wall of which it 

 is composed is built up of minute, firm, closely -com- 

 pacted cells, resembling externally, on a very small scale, 

 the irregular pattern so frequently seen belonging to the 

 epidermis of many leaves, as of the pea. Towards the 

 base of the perithecium certain privileged cells throw out 

 curved unbranched processes or tentacle-like filaments of 



