[VOL. 2 



328 



ANNALS OF THE MISSOURI BOTANICAL GARDEN 



carp. This in turn fuses with the two other large cells of the 

 basal portion of the procarp, thus forming the large fusion 



cell from which the 

 gonimoblasts, or sporog- 

 enous threads arise 

 (Twiss, '11). 



4. In Harveyella mi- 

 rabilis,^ a large cell 

 which gives rise to the 

 four-celled procarp is 

 the auxiliary cell. A 

 short ooblastema fila- 

 ment from the egg con- 

 nects with the latter, 

 which becomes the cen- 

 tral cell. 



5. In Callithamnion 

 (Ceramiales) the fusion 

 (diploid) nucleus in the 

 egg divides into two. 

 Two short ooblastema 



Cf.br 



Fig. 6. A, Harveyella mirahilis; B and C, 

 Erythrophyllum delesseroides ; D, E, F, and G, 

 Callithamnion corymbosum: cpbr, carpogonial 

 branch; cpg, carpogonium; tr, triehogyne; of, 

 ooblastema filament; ac, auxiliary cell; g, 

 gonimoblast; fc, fusion cell. 1, 2, and 3 are the 

 three large basal cells of the procarp in Ery- 

 throphyllum which fuse with the ooblastema 

 filament to form the fusion cell. Shaded por- 

 tions are diploid; note that in the fusion cell 

 of Callithamnion the vegetative nucleus (hap- 

 loid) remains at a distance from the diploid 

 nucleus. — A, after Sturch; B and C, after 

 Twiss; D, E, F, and G, after Oltmanns. 



filaments proceed from 

 the carpogonium, each containing a diploid nucleus, and fusing 

 with an auxiliary cell at the side of the base of the procarp. 

 Each of the two auxiliary cells now contains two nuclei. A 

 wall divides each cell into two. The upper daughter cell con- 

 tains the diploid nucleus and becomes the central cell, giving 

 rise to the sporogenous threads, while the haploid nucleus in 

 the lower cell degenerates (Oltmanns, '04). 



6. The most complicated type may be represented by 

 Dudresnaya purpurifera (Cryptonemiales) where several 

 ooblastema filaments arise from the sterilized egg cell. These 

 fuse with auxiliary cells which are either certain cells of the 

 procarp branch, or terminal cells of its branched system, or 

 of more distant ''secondary procarp branches." An oobla- 



^ H. mirahilis is parasitic on certain species of Polysiphonia, and is devoid 

 of chlorophyll. For this reason it is regarded by some as indicating a step in the 

 direction of an ascomycete. 



