

2SS BOTAXICAL GAZETTE [april 



growth. Upon this subiculum compact masses of hyphae develop 

 as minute, snow white knobs. These represent the primordia of 

 fruit bodies. 



Development of the ascocarp. — The youngest fruit body 



sectioned measures slightly less than 0.3 mm. in lateral diameter. 

 A considerable number of others possess a maximum diameter of 

 1 mm. or less. The youngest fruit body studied (tig. 2) is a wholly 

 undifferentiated "button" of mycelium. The hyphae making up 

 the primordium arise in this case from about a small rootlet, and 

 pushing upward between other rootlets run more or less distinctly 

 parallel toward the surface of the ground, where they radiate in 

 every direction, giving the primordium its rounded form. At this 

 early stage there is no indication of sexual cells, and no evidence 

 other than shape that this "button" of mycelium is to develop 

 into a fruit body. 



The hyphae at the surface of the primordium form a more or 

 less definite palisade layer, although at this early period they are 

 sufficiently flexuous to destroy the very definite palisade effect 

 evident later. These hyphae in many cases can be traced backward 

 with ease to the point of origin of the fruit body. No structure 

 of the nature of an enveloping veil is present, and it is incredible 

 that one could have existed at an earlier period. Neither in this 

 nor in any later stage has the writer been able to find remnants 

 of a ruptured envelope such as that figured by McCubbin (25) for 

 Helvetia elasiica. He has searched for these in sections of many 

 very young fruit bodies and is absolutely convinced that in Rhizina 

 undulata the ascocarp is at no stage provided with a veil. The 

 fruit body is therefore gymnocarpous and the hymenium is " exposed 

 from the first." Fig. 2 shows in median longitudinal section a 

 fruit body of Rhizina undulata considerably younger than the 

 youngest stage photographed by McCubbin in Helvetia. The 

 deep-staining spots at the side and base of the primordium are 

 transverse sections of pine rootlets. 



McCubbin states that in Helvetia elastica "the envelope which 

 covers the fruiting body in its early stages arises from the palisade 

 layer. Many of the club-shaped hyphae of the latter continue to 

 grow out beyond the general surface, then turn at right angles, 



