ATKINSON: THE GENUS ENDOGONE 11 



zygocarp with a definite and well-developed peridium. This repre- 

 sents a distinct progression in development over all other phycomy- 

 cetes, a cephalization of zygotes into a complex fruit body. 



The heterogamous character of the gametangia of Endogone lacti- 

 flua and the selection of a single gamete nucleus in each are oomycete 

 features. But the lack of differentiation in the cytoplasm in the 

 GOgone, or gametangia, is a zygomycete feature. For these reasons 

 Bucholtz^ interprets Endogone as occupying an intermediate position 

 between the zygomycetes and Oomycetes, but constituting a distinct 

 group, the Endogoneae.^ He probably regards this intermediate posi- 

 tion as simply taxonomic, not phylogenetic. 



Relation of Endogone to the Ascomycetes 



Endogone has been shifted in all the three great divisions of the 

 fungi. It was first placed in the Basidiomycetes near Khizopogon by 

 Link (1809) who was followed by Fries (Syst. Myc. 2, 295, 1822). 

 For a long time it has remained in the Ascomycetes, being placed in 

 the Tuberaceae by Vittadini (1831), by Tulasne (1857), by Saccardo 

 (Syll. Fung. 8, 905, 1889). Schroeter (1889) placed Endogone with 

 some uncertainty in the Order Protomycetes, the highest order of the 

 Phycomycetes. He was followed by Saccardo (Syll. Fung. 14, 829, 

 1899), and it is significant that the genus Protomyces has by many 

 students been placed in the Phycomycetes. In 1897 Schroeter, while 

 still retaining Endogone in the Protomycetaceae, transferred the group 

 to the Hemiascineae. 



Until we know the morphological and cytological phenomena in 

 connection with the germination of the resting zygotes of Endogone 

 we cannot say with any degree of precision what relation it bears to 

 the Ascomycetes, nor how near that relation is. It appears quite 

 probable that Endogone does bear an interesting relation to the 

 Protoascomycetes. If the resting zygotes germinate fructificatively 

 with free cell sporulation, somewhat as occurs in Dipodasciis or 

 Protomydes, its relation to the Protoascomycetes would be very clear. 

 The question would then arise whether with its coenocytic mycelium 

 it should be placed on a level with Dipodasciis or just below it, repre- 

 senting the highest level of the Phycomycetes. Even if the germina- 

 tion phenomena should prove to be of the phycomycete type, Endo- 



^ He describes two large nuclei in the zygote of E. ludwigii, a sexual species. 



'" The genus has been considered for a long time by a number of students to 

 represent a distinct family. Fries (Summa Veg. Scand. 1849) proposed the 

 family Endogonaceae and in view of Bucholtz's studies it is interesting to note that 

 Schroeter in 1889 placed it along with Protomyces as the highest member of the 

 Phycomycetes. 



