General Features 289 



The process here is exacth' the same except that in the fungus 

 the ascostome stretches in order to produce a tight fit, while in 

 the potato gun the potato plugs contract for the same reason. 

 In the potato gun the force is applied by the human muscle 

 while in the ascus it is supplied by osmotic pressure. And again 

 the form of the spore is such that, as previously suggested, after 

 the spore has passed its center the contraction of the stretched 

 ascostome accelerates the force with which it is shot out, as a 

 lemon seed may be shot from between the fingers. 



Recently Aliss EUys Butler (Mycologia 31: 612-623./. 12. 

 1939) has noted the same method of spore discharge in Patellaria, 

 one of the inoperculate discomycetes. In that case, however, 

 the process takes place by slow motion so that it can easily be 

 followed (Fig. 22). A more complete discussion of this is under 

 the subtitle Classification (page 296). 



According to Boedijn the waiter seems to have been the first 

 to call attention to the constancy of the delicate striate markings 

 on the spores of the species of these two genera. He claims, 

 however, that there are delicate longitudinal ridges. These 

 marks are suggestive of the rifling of a gun barrel, and it ma\- be 

 that they too are concerned with the methods of spore discharge. 



Dehiscence of the Ascus (page 15) 



In the introductor\- chapter it was stated that there were 

 three types of ascus dehiscence. A fourth type has since been 

 discovered in the discomycetes, and this will be treated more in 

 detail under the subheading Classification. 



Eccentricity of the ascostome (page 17) 



In our first edition the writer having discussed the eccen- 

 tricit\- of the ascostome finalh" concluded from numerous ob- 

 servations that this was a fixed character in the asci of species of 

 certain tropical genera, especialh' Pliillipsia and Cookeina. Thus 

 two theories have been offered : 



Dr. A. H. R. Buller noted this character in a Canadian species 

 described in this work as Plectania hiemalis (p. 193, pi. 19, f. 2). 

 Since the cups of this species happen for the most part to be 

 deep funnel-shaped he concludes that the eccentricity of the 

 ascostome is an adaptation to this character and designed to 

 throw the spores up through the mouth of the cup instead of 

 shooting them across into the opposite wall. This is a very 



