ENDOTHIA PAKASITICA AND RELATED SPECIES. 23 



on Quercus alba and Q. prinus, E. parasitica produced the typical 

 mycelial fans. 



Anderson (1, p. 14) considers that the occurrence of these fans 

 is associated with the parasitic habit of the fungus. In his opinion 

 single hyphae do not possess the power of penetrating the living cells, 

 but the fungus grows on the injured and dead cells about a wound 

 until a quantity of mycelium is accumulated, when it "en masse 

 pushes through the living tissues of the bark." This view is also 

 held by Keefer (45, p. 193), who adds that "the action of the ad- 

 vancing mycelial mats seems to be physical rather than chemical, 

 and the cells are mechanically broken to pieces." 



Kankin, however, states (62, p. 248) that "The host cells, just 

 in advance of the edges of the fan, are disintegrated and form a 

 distinct gelatinous band, which can be seen with the naked eye." 

 This observation suggests to the writers that some toxic or enzymatic 

 action upon the cells of the host probably occurs before the cells 

 are actually invaded by the fungus hyphse. Careful investigation 

 of this point should go far toward determining the causes of the 

 parasitism of this fungus. Whatever the cause or function of these 

 fans, they are very characteristic, and the writers have found them 

 invariably in diseased material of Castanea in America, as well as 

 in that from China and in two specimens of E. parasitica on Quercus. 



A similar mycelial formation, fanlike in form, 1 is produced by 

 Armillaria mellea in the bark of roots attacked by this fungus. Ex- 

 cellent specimens of the Armillaria mycelial fans have been pre- 

 sented to the writers by Prof. Wm. T. Home, of the University of 

 California. 



STROMATA. 



Under the name Melogramma gyrosum, in which they included 

 specimens of both Endothia gyrosa and E. fluens, the Tulasnes (83, 

 pp. 87-89) described the structure of Endothia in some detail. Their 

 description was based chiefly on abundant local material of E. fluens 

 collected on Carpinus ~betulus L. during several years, but they also 

 used material sent by Guepin from western France, pycnidial ma- 

 terial on chestnut from Italy, American material sent by Schweinitz 

 to Brongniart and preserved in the Paris Museum, and specimens 

 from Carolina sent by Berkeley. According to the Tulasnes (83, 

 p. 87 ) 2 the stromata are "developed singly and emerge gradually 

 as so many scattered points with fibers radiating in all directions, 

 soon swell into a yellowish cone, rupture the epidermis above them, 



1 Since this manuscript was completed a very similar mycelial formation has come to 

 the writers' attention. As figured by Nowell (50), pi. 1, Rosellinia pepo, when growing 

 under the bark of lime trees, forms mycelial fans resembling those of Endothia parasitica. 



2 The portions in quotations are rather free translations of the authors' Latin. 



