FORMATION OF SPORES 53 



activity of the fibrillae of an aster attached to each nucleus. 

 These fibrillae rotate and bend down around the nucleus 

 from the centre of the aster, and delimit a certain amount 

 of protoplasm which, after becoming rounded off and 

 bounded by a wall, constitutes a spore. After the forma- 

 tion of the spores is completed, a certain amount of unused 

 protoplasm, now termed epiplasm, remains in the ascus, 

 which, being without nuclei, undergoes disintegration. 

 Spores produced in asci are often called ascospores. Harper 

 suggests that the term ' free cell formation ' should be con- 

 fined to cells formed as described above. The two char- 

 acteristic features of the process are, the cutting out of the 

 mass of protoplasm that forms the spore by the activity of 

 the fibrillae of an aster, and the presence in the ascus of an 

 amount of epiplasm, or surplus protoplasm, after the spores 

 are formed. This method of spore-formation has been 

 observed in widely separated members of the Ascomycetes ; 

 it is not, however, universal. Guilliermond states that in 

 Peziza rutilans^ where the nuclei are exceptionally large, 

 the nuclear membrane disappears during division, and 

 there is no evidence of the existence of either centrosomes 

 or asters. In Taphrina Johansoni^ according to Ikeno, the 

 process of spore-formation in the ascus does not conform 

 with the method described by Harper, neither is it due to 

 cleavage lines as in the Phycomycetes. Two nuclei present 

 in the young ascus fuse and form a nucleus with a very 

 conspicuous nucleolus. The nuclear membrane disappears, 

 and the nucleolus, which appears to be chromatic in nature, 

 undergoes fragmentation without any sign of mitotic divi- 

 sion. The chromatin fragments collect in groups in 

 vacuoles, and each group attracts a certain amount of pro- 

 toplasm, which becomes surrounded by a wall and forms a 



