144 



COMPARATIVE MORPHOLOGY OF FUNGI 



cells, but by the fission of the mother cell so that both daughter cells 

 round off and develop to the size of the mother cell (cell division, in 

 contrast to sprouting) . 



When the mycelium is ready to form asci, it assumes a characteristic 

 habit: it branches into numerous, short, slender branches with short cells 

 which contain only a small number of nuclei, often only one (Fig. 89, 3 

 and 4). The branches end either in a very large cell full of reserves, the 

 female copulation branch, or in a narrow, often twisted branch with 

 hyaline content, the male copulation branch. The upper third of the 

 female copulation branch swells considerably and collects the cytoplasm 



Fig. 89. — Endomyces Magnusii. 1. Young multinucleate hypha. 2. Older hypha. 

 3 to 13. Development of asci. 14. Gemmae. (1, 2, 14 X 1,500; 3 to 13 X 500; after 

 Guillermond, 1909.) 



with two or three nuclei. At the beginning of copulation, it bends over 

 somewhat to meet the male copulation branch. In this stage, the 

 swollen part contains only one nucleus, the others have migrated down- 

 ward (Fig. 89, 5). The narrow male copulation branches contain one to 

 three nuclei when young, of which only one remains at the tip. 



In approximately three-fourths of the cases, copulation occurs 

 between the male and the female copulation branches. The male 

 copulation branch approaches the female, swells slightly and ab joints the 

 apical uninucleate gametangium from the stipe cell. Meanwhile the 

 uninucleate tip of the female copulation branch is ab jointed 

 from the stipe cell. Hereupon the walls separating the gametangia 

 are dissolved and the zygote develops to a 4-spored ascus (Fig. 89, 6 to 8). 



