MICHIGAN ACADEMY OF SCIENCE. 119 



are greater in their horizontal than in their vertical (liniensioii. 

 The sizes of the jucnitlja vary from 1/10 to Mi of a niilliiiu'ter. 

 Thus same variation in size is fomul in ]»ycni(lia ])r()(lnc('(l in media 

 and seems to be related to nutrition. 



The relation of the jncnidia to the wood and bark is very im- 

 portant since it determines the classification of the organism. The 

 pycnidia which (Kciir cm the dead bark, either submerge 1 or partly 

 submerged, may by weathering of the bark become wholly exposed. 

 When the pycnidia are borne on the wood the base is formed on 

 and ill the outer wood fibres by a loose felting together of the 

 hyphae and this part of the wall eventually becomes cai-bonaceous 

 pseudoparenchyma. When a pycnidinm is broken from the wood 

 a definite ring is left. There is no definite pushing up of the pycni- 

 dinm, as in i'ii/hacropsis malonnn, accompanied by rifting of the 

 bark. The pycnidia vary greatly with regard to the ostiole. A 

 few pycnidia have a marked l)eak, especially in culture. In other 

 cases, the pycnidia are pear shaped. In old dried material, the 

 morphology in this regard is vei*y hard to decipher. 



The walls of the ])ycnidium are thick and composed of two dis- 

 tinct layers. The outer is brown or black and made up of small 

 cells with thick walls. The inner layer is hyaline but with distinct 

 large cells. The outer wall is covered with hyjihae as the pycnidia 

 grows in culture, but smooth and shining as the fungus is fomid in 

 nature. Within, the walls of the- pycnidinm bristle with conidio- 

 phores which arise' from the sides and base. The base is frequently 

 much thickened and the beginnings of foldings and convolutions- 

 in this hymenium are evident. 



The conidiophores are about two times the length of the spores.. 

 They are swollen at the base, and pointed at the apex. Frequently 

 two cling together in material from young pycnidia. These conidio- 

 phores are hyaline and filled with a granular jn'otoplasm. The 

 sjjores are cylindrical with blunt, rounded ends. Occasionally a 

 spore will show a slight curve. In mass the spores have a slight 

 greenisii or hrowu tinge. If the spores are viewed singly, the 

 deviation fiom hyaline can hardly be detected. The spores have 

 never been observed to push out in long tendrils, but in some nmist 

 cultures a little globule of spores will be protruded. This globule 

 is yellowish when fi-esli but it becomes brownish with age. 

 The following table gives a sunnnary of some measurements: 



