1918] FITZPATRICK—RHIZINA 207 
best known example, several pairs of ascogonia and antheridia 
contribute to the formation of a single apothecium. In the majority 
of the Discomycetes which have been studied, however, a single 
archicarp is developed. Of these may be enumerated Lachnea 
scutellata (BROWN 12, WORONIN 69), Peziza granulosa and Ascobolus 
pulcherrimus (WORONIN 69), Ascobolus furfuraceus (JANCZEWSKI 
45, 46, HARPER 39, WELSFORD 65), Ascodesmis nigricans (VAN 
TIEGHEM 61), Ryparobius sp. (BARKER 4, 5), Thelebolus stercoreus 
(RAMLOw 57), Lachnea scutellata (BROWN 12), Humaria granulata 
(BLACKMAN and FRASER 9g), Ascophanus carneus (CUTTING 18), 
and Lachnea cretea (FRASER 30). As representative of lichens 
containing several archicarps in a single apothecium may be listed 
Parmelia acetabulum (BAuR 7, 8), Anaptychia ciliaris, Lecanora 
subfusca, Endocarpon miniatum, Gyrophora cylindrica, and Cladonia 
pyxidata (BAUR 8), Pertusaria communis and Pyrenula nitida 
(Baur 7), and several species of Collema (BAUR 6, BACHMANN 2, 3). 
The individual archicarp of R. undulata arises by the rapid 
growth and transformation of a single multicellular hypha. The 
cells increase greatly in lateral diameter and become filled with 
deeply staining protoplasm, so that the resulting structure assumes 
a dense and opaque appearance. The relatively few nuclei origi- 
nally present undergo repeated division, and each cell of the archi- 
carp is soon packed with many nuclei. The cells of the archicarp 
are certainly multinucleate from the first. In Ascobolus, according 
to HARPER (39) and Wetsrorp (6s), the cells of the archicarp are 
uninucleate at the beginning, while in other forms (BROWN 12 
Lachnea scutellata, Cuttinc 18 Ascophanus carneus) they are 
described as multinucleate in all stages. 
The diameter of the cells of the archicarp when the ultimate 
size is reached is much greater than that of the surrounding hyphae, 
and for this reason no possibility exists of mistaking an archicarp for 
an ordinary hypha, even when the lower powers of the microscope 
are used. This difference in size is strikingly shown in fig. 4. 
Cells of a mature archicarp sometimes measure 10 times the 
diameter of the other hyphae. 
The archicarp is in all cases multicellular, the number of cells 
varying in the counts made from 10 to 19. Different individuals 
