186 SPORE DISSEMINATION 



sorbent paper in a moist chamber. This fungus possesses a sub- 

 conidial bulb, and a line of dehiscence consisting of two mem- 

 branes in apposition develops toward the base of this bulb. The 

 upper membrane is the more elastic. When, with increased 

 turgor inside, the rupture of the conidiophore takes place along 

 the line of separation, the upper part of the bulb, which is least 

 extensible, contracts, and the basal septum bursts. The effect is 

 that the sap is squirted backward, carrying away all parts above 

 the line of dehiscence on the recoil. During the rocket-like flight 

 the conidium may become separated from the adhering upper 

 part of the subconidial bulb or may fail to separate. The conidio- 

 phore tip pushes into the conidium at the juncture to effect separa- 

 tion, just as it does in Entomophthora. 



Evidently all Entomophthorales, except perhaps Massospora, are 

 capable of forcibly liberating their spores. 



SPORE DISCHARGE AMONG ASCO.MYCETES 



Spore discharge among erysiphaceae. As mi^ht be antici- 

 pated, cleistocarpous fungi, such as the powdery mildews, require 

 a mechanism to liberate their spores that is quite unlike that of 

 Pyrenomycetes and Discomycetes. Ingold (1939) has assembled 

 the observations made on spore liberation among the Erysiphaceae. 

 According to him, there are two types of spore liberation in this 

 family. In Sphaerotheca mors-ircae, which illustrates one type, 

 the cleistothecium remains dormant throughout winter, but in 

 spring the single ascus swells to the extent of causing the cleisto- 

 carp wall to rupture, permitting the ascus to protrude through 

 the fissure. The protruded ascus continues to swell, finally burst- 

 ing in a thin region at the tip and squirting out the ascospores. 



In 1884 the other type of discharge was graphically described 

 for Erysiphe by W. G. Smith [Ingold (1939) ] as follows: "When 

 they [the cleistocarps] burst, the contained bladders or asci often 

 burst at the same time, and the living sporidia, after their six 

 months' rest, fly into the air. At other times the bladders or asci 

 themselves fly out of the perithecia, and sail, each with its little 

 load of eight sporidia, through the air. When in the air, the asci 

 burst, and the spores are set free into the atmosphere." This type 

 might well be called the rocket type of discharge. The operation 



