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264 MONOGRAPH OF THE LABOULBENIACE^ 
Family LABOULBENIACE^ Peyeitsch. 
DIMOEPHOMYCES Thaxter. Plate V, figs. 1-16 
m 
Proc. Am. Acad. Arts and Sci., Vol. XXVIII, p. 157. 
Dioecious. Mule indlvidiuil consisting of four superposed cells, the two distal ones sterile, 
the sub-basal producing a compound antheridium, the six antheridial cells of which are arranged 
in two antero-posterior rows and discharge into a common cavity lying above them, from which 
the antlicrozoids escape through a prominent tubular neck. 
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Female indh'ulml consisting of four superposed cells, the two distal ones sterile, the si:b-basnl 
cell <nving rise to two or more perithecia and sterile appendages wliicli alternate with one another 
on cither side, forming a transverse series. Trichogyne short, radiatcly branched- spores once 
septate. 
The material available for the illustration of this genus, although abundant, includes, uufor- 
tuuatcly, no young individuals in which the first stages in the development of the primary peri- 
thecia are shown. Owing to the small size of the plant and the indistinctness of its septa, it 
has been difficult to determine with certainty the exact relation which the perithecia and sterile 
appendages bear to the receptacle. While in most cases tlie latter has seemed to consist of 
three superposed cells, as in fig. 1 or 5, in a few specimens I have thought that there was nn indi- 
cation of the presence of septa as is indicated in fig. 4. If the first of those alteruafivcs proves 
to be correct, the portions of the receptacle which bear the appendajrcs and perithecia must be 
considered as wing-like outgrowths from the basal cell ; while in the second instance they would 
originate from a sub-basal cell. Although in no other genus, with the excci)ti.)n of Amor- 
phomyces,^ is anything approaching a similar condition found, I am inclined to think that the 
first-mentioned alternative is the correct one. 
Tn form and development the species of Dimorphomyces are very peculiar. There is a gen- 
eral triangular outline to the portion below the sterile cells of the receptacle, a tendency to a 
posterior convexity and anterior concavity ; and in both species the first organs to be developed 
are a pair of primary perithecia symmetrically placed and followed immediatelv bv a strrile 
3) 
be 
' ^"^ ''^'^' commonly two or four secondary perithecia are formed, alter- 
natmg with as many sterile appendages. The process by which these organs are formed is unlike 
any corresponding process in other genera. Assuming that my observations arc correct in de- 
In?. ;; "f V"^t''' eell of the receptacle, the first step in their formation would 
^ r^r ^K^r i:r:^!r'^'''- ^-- ^^^ -^^ ^^--tncally placed on either 
cparatcd 
valnr^c, ti^^-. 1 ' L . , . * -^ "" ^^^^ ^"'^ ^i^G ceil inus scparatcu uu- 
.elops upward mto a pentheoum. Meanwhile a lateral prolitcratiou takes plaee below this 
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